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The Current Practices and Perceptions of the Low Iodine Diet
in the Treatment of Thyroid Cancer
ABSTRACT
Low-iodine diet (...
provided to their patients. Similar discrepancies were also observed in dietitians and
patient information handouts. This ...
left after surgery, the radiation dose delivered by I-131, the initial dose rate, and the
uptake of I-131 in the neck. (3)...
CURRENT PROBLEMS
1. Some physicians and institutions do not support the need for dietary
modifications prior to and/or aft...
1. To conduct a literature review on the recommendations made on the LID. This
included the effectiveness of the diet, the...
professionals were invited to comment on the preliminary questionnaires as they either
had the expertise on the subject of...
b) Questionnaire for Dietitians
A convenience sample of 24 dietitians was included in this study. Local dietitians
from ea...
For open-ended questions, comments were collated and compared with the
recommendations made in current literature.
Patient...
of iodine, but also increases serum thyrotropin (TSH) production, resulting in an
increased uptake of I-131 by thyroid tis...
body iodine depletion first emerged in a study published in 1965. (12) Several other
studies in the 60’s that have investi...
The next study was published in 1983 in which Maxon et al studied 40 patients
between 1974 and 1982. (5) In this study, ni...
(< 25 ug iodine daily), a diuretic (hydrochlorothiazide or furosimide), 12 g sodium
chloride, and 3 litres of water, daily...
amounts of milk and eggs. (8) Differing from the diet proposed by Maxon et al, the
specific type and amount of foods allow...
that a LID might allow patients to be treated with smaller dosages of I-131. (3) Differ
from the predictions made by Gosli...
procedure were compared between both diet groups. (22) It was found that the 24-hour
urinary iodine excretion by LID durin...
above facilities did not respond to the questionnaire. Therefore, the data summarized
below might not represent the full p...
the procedure. The total number of days that patients were recommended to stay on the
diet by their physicians ranged from...
give verbal instructions at the time of obtaining consent. This was because some
patients might have been put on a LID pre...
FIGURE 1: Written instructions provided by physicians
FIGURE 2: Verbal instructions provided by physicians
0 1 2 3
No Eggs...
Only 2 out of 6 physicians have received feedbacks on their written and/or verbal
LID instructions from their patients. On...
might be marginally effective if iodine uptake was poor. However, he also felt that it
would be very difficult for patient...
whether he/she would consider referring his/her patients to a dietitian. This physician
said it would depend on the availa...
Questionnaire for Dietitians
Of the 24 questionnaires sent to dietitians, 15 were completed and returned
(response rate: 6...
Only 3 dietitians commented on the question regarding the level of iodine intake
restriction that their patients have foll...
version of an old 1990s diet they had on file, while the other said that she was mainly
using their old hospital diet hand...
When the dietitians were asked when their written instructions were last updated,
only one dietitian reported that it was ...
FIGURE 4: Verbal instructions provided by dietitians
Note: This bar graph does not truly reflect the type of verbal instru...
and difficult to understand”, “the diet was unpalatable”, and “it was overwhelming to
maintain the diet while adapting to ...
wanted to comply with a more rigid diet because they believed that it must be better to
follow a strict LID.
Similar to th...
She believed that when the diet was reviewed for the region, the physician was the one
who was advocating for its inclusio...
be. She thought it would still be a good idea to limit the diet iodine in case it does help
treatment until proven otherwi...
It should be noted that the following table only summarizes the diet instructions
provided by each hospital’s official die...
TABLE 3B: Patient general diet information provided by St. Paul’s Hospital
Name of
Hospital
Availability
of a LID
Handout
...
TABLE 3C: Patient general diet information provided by Surrey Memorial Hospital and
Kelowna General Hospital
Name of
Hospi...
Name of
Hospital
Availability
of a LID
Handout
Duration of
Diet
Availability
of a List of
“Food
Allowed”
and “Foods
to Avo...
Name of
Hospital
Availability
of a LID
Handout
Duration
of Diet
Availability
of a List of
“Food
Allowed”
and “Foods
to Avo...
Name of
Hospital
Availability
of a LID
Handout
Duration
of Diet
Availability
of a List of
“Food
Allowed”
and “Foods
to Avo...
Hospital of a LID
Handout
of Diet of a List of
“Food
Allowed”
and “Foods
to Avoid”
Diet/Nutrition
Information
Provided
of ...
Name of
Hospital
Availability
of a LID
Handout
Duration
of Diet
Availability
of a List of
“Food
Allowed”
and “Foods
to Avo...
In summary, it is apparent that not every facility is providing information on LID
(or any form of diet) to patients recei...
b) Food Allowed
The following table (Table 4) summarizes the foods that are allowed in a LID as
indicated on the diet and/...
TABLE 4 (continued): A comparison table that shows what foods are allowed in the LIDs of 5 facilities
Food Group Food Item...
TABLE 4 (continued): A comparison table that shows what foods are allowed in the LIDs of 5 facilities
Food Group Food Item...
TABLE 4 (continued): A comparison table that shows what foods are allowed in the LIDs of 5 facilities
Food Group Food Item...
- Tomatoes x x
TABLE 4 (continued): A comparison table that shows what foods are allowed in the LIDs of 5 facilities
Food ...
TABLE 4 (continued): A comparison table that shows what foods are allowed in the LIDs of 5 facilities
Food Group Food Item...
meats, sausages,
frankfurters)
TABLE 5 (continued): A comparison table that shows what foods should be avoided as indicate...
only) OK)
TABLE 5 (continued): A comparison table that shows what foods should be avoided as indicated on the
LID handouts...
ingredients
TABLE 5 (continued): A comparison table that shows what foods should be avoided as indicated on the
LID handou...
iodine
Mustard x x x
TABLE 5 (continued): A comparison table that shows what foods should be avoided as indicated on the
L...
DISCUSSION
To date, existing literature have all demonstrated a positive relationship between
I-131 uptake in the thyroid ...
demonstrated by more studies, more research on their relationship is still warranted. (3)
In the mean time, Morris et al s...
questionnaires from dietitians. This was somewhat closer to what literatures have
recommended. In addition to the inconsis...
content of their patient diet handouts were very different from each other. As these
have already been described in detail...
was also similar to the restriction level recommended by various literature studies.
Currently, the Daily Recommended Inta...
more up-to-date, patient-friendly information could be provided without confusing and
causing anxiety in their patients. T...
It is said that the average Canadian’s daily intake of iodine is 1000 ug. (20)
However, it was difficult to estimate the i...
1. As suggested by Pluijmen et al, it is sufficient to start a LID 4 days prior to the
I-131 procedure. (22) During a rece...
multivitamin/mineral supplements contain only a very small amount of iodine,
and its benefits to some patients whose food ...
multivitamin/mineral supplements contain a large dose of iodine. Continuation
or avoidance of the use of multivitamin/mine...
c. Commercial breads and grain products made from bread dough. (3, 5,
8, 16, 22), This is because the dough oxidizers or c...
meat, vegetables, fruits, grains and cereals are also generally lower than
foods such as iodized salt and seafood. Therefo...
Appendix 3 shows the iodine content of foods. It is an excerpt from a book called
Nuclear Medicine Therapy by Harbert J.C....
The Current Practices and Perceptions of the Low Iodine Diet
The Current Practices and Perceptions of the Low Iodine Diet
The Current Practices and Perceptions of the Low Iodine Diet
The Current Practices and Perceptions of the Low Iodine Diet
The Current Practices and Perceptions of the Low Iodine Diet
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The Current Practices and Perceptions of the Low Iodine Diet

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The Current Practices and Perceptions of the Low Iodine Diet

  1. 1. The Current Practices and Perceptions of the Low Iodine Diet in the Treatment of Thyroid Cancer ABSTRACT Low-iodine diet (LID) has been prescribed by some physicians in an attempt to deplete the thyroid of its natural stores of iodine in cancer patients receiving radioactive iodine (I-131) scans and treatments. Despite the emergence of the low-iodine diet since the 1960s, there have been very limited conclusive studies on the true efficacy of LID in the treatment of thyroid cancer. This results in various discrepancies in the practices among physicians and dietitians who may or may not recommend LID. The purpose of this study was to examine the current practices and perceptions of LID among medical and dietetic practitioners in British Columbia (BC) and across Canada. Literature research on LID was completed through Medline and Pubmed searches. Two questionnaires were developed and distributed to twenty-two BC physicians and twenty- four BC and out-of-province dietitians. Information handouts for I-131 patients from seven BC and out-of-province facilities were also compared. After analyzing the findings from the questionnaires and the patient information handouts, it was proved that the practices and perceptions of LID varied significantly between facilities, or even between physicians and dietitians within the same facility. Some physicians did not recommend the diet at all. For those who recommended the diet, their personal beliefs towards it were very diverse. These discrepancies resulted in inconsistent physicians’ practices in terms of the procedure in which the diet was prescribed for, the duration of diet they recommended, the level of iodine intake restriction required, their chosen route of delivering recommendations, and the actual verbal and written instructions they
  2. 2. provided to their patients. Similar discrepancies were also observed in dietitians and patient information handouts. This study has confirmed the inconsistencies of current practices and perceptions of LID among physicians and dietitians. It has concluded that there is a necessity to standardize the current LID recommendations provided by all involved health professionals. Recent studies have demonstrated that a LID can improve the efficacy of thyroid remnant ablation, and that a less stringent diet with a shorter duration (i.e. 4 days instead of the traditional 7 to 14 days) can achieve similar clinical outcomes. There seems to be a need for facilities to update their LID recommendations and adopt a more liberalized approach. Suggestions for doing so were included in this study. It is the goal for patients to benefit from the liberalized LID, while the level of restriction will not compromise their psychological well being and their compliance to the diet. INTRODUCTION Total thyroidectomy is commonly the initial treatment chosen for patients who have been diagnosed with well-differentiated thyroid carcinoma. (1) Following surgery, radioactive iodine (I-131) scanning is usually performed to ensure that no residual tumor is present in the neck. (1) In the majority of patients with thyroid residual disease, high dose (> 100 mCi) I-131 ablation therapy will be done to destroy cancer remnants and prevent disease recurrence. (1, 3) A number of factors play a significant impact on the effectiveness of the dose, and hence, the likelihood of successful ablation. (3) These factors include: the severity of the initial disease, the amount of residual thyroid tissue
  3. 3. left after surgery, the radiation dose delivered by I-131, the initial dose rate, and the uptake of I-131 in the neck. (3) Early studies have demonstrated that the iodine-concentrating capacity of tumor cells is less effective than normal thyroid cells. (1, 10, 11) As well, the total amount of radiation that can be given to an individual is limited due to the cumulative effect of total- body radiation on the hematopoietic system. (1) It is a concern that there are depressing effects of over dosage of I-131 on bone marrow. (10) As a result, it is important to maximize the uptake of I-131 by thyroid cancer remnants. (1) Among the various methods to enhance cancer tissue uptake of I-131, a low-iodine diet (LID) has been prescribed by some physicians. The premise of a low-iodine diet is to deplete the body (and in particular, the thyroid) of its natural stores of iodine, so that the I-131 scan and/or treatment can become more effective. (2) The rationale of this practice is that when I-131 is administered, the thyroid will “suck up” the iodine because it has been so depleted of its natural stores. (2) Currently, thyroid cancer patients in British Columbia (BC) are followed up by physicians from one of the four BC cancer centres, namely Vancouver Cancer Centre, Fraser Valley Cancer Centre, Vancouver Island Cancer Centre, and Cancer Centre for the Southern Interior. For patients who require I-131 scans and/or treatments, they will be referred to one of the five hospitals in BC that offer such procedures. These hospitals include: Vancouver General Hospital, St. Paul’s Hospital, Surrey Memorial Hospital, Kelowna General Hospital, and Royal Jubilee Hospital.
  4. 4. CURRENT PROBLEMS 1. Some physicians and institutions do not support the need for dietary modifications prior to and/or after the I-131 scans and treatments. 2. Existing guidelines for the LID vary among physicians, dietitians, and institutions offering I-131 procedures. Inconsistencies in the existing guidelines include: a) Level of iodine intake restriction b) Duration of diet prior to and/or after the procedure c) Use of diet for scans and/or treatments d) Quality of the dietary information for patients i. Verbal instructions and/or written instructions ii. Food lists (allowed and avoided) iii. Use of multivitamin or calcium supplement iv. Use of distilled water 3. Patients often consult dietitians for clarification of necessary dietary modifications. A research on current literature is essential in order to provide the most up-to-date and accurate information to patients. PURPOSE OF THE STUDY In light of various discrepancies of the use of LID among physicians, dietitians, institutions and clinical studies, it was the purpose of this research study to examine the current practices and perceptions of physicians and dietitians about the use and efficacy of this diet, and to compare them with the recommendations made in existing literature. To be more specific, this study included the following components:
  5. 5. 1. To conduct a literature review on the recommendations made on the LID. This included the effectiveness of the diet, the level of iodine restriction required, the procedures in which the diet is prescribed for, and the optimal length of time a patient should follow such a diet. 2. To examine the current practices and perceptions of the LID among medical and dietetic practitioners. Pool of subjects included physicians referring patients for I-131 scans and/or treatments, physicians performing I-131 scans and treatments in hospitals across BC, and dietitians receiving referrals for LID counseling in BC and across Canada. 3. To examine and compare the type of diet information provided by the nuclear medicine department of each of the five hospitals. SUBJECTS AND METHODS Literature Review Literature review was first completed through electronic journal databases (e.g. MEDLINE and PUBMED), in addition to the references cited in pertinent articles. Results of these studies and their recommendations were summarized. Electronic Questionnaires Two electronic (online) questionnaires were developed using a combination of qualitative and quantitative questions (see Appendices 1 and 2). To ensure that the questions would provide the information being sought and would not be misinterpreted, the questionnaires were reviewed by a physician and three dietitians who were either working at the Vancouver General Hospital or Vancouver Cancer Centre. These health
  6. 6. professionals were invited to comment on the preliminary questionnaires as they either had the expertise on the subject of interest or extensive experience on questionnaire development. Revisions of the questionnaires were made based on the comments received. a) Questionnaire for Physicians A convenience sample of 22 physicians was included in this study. Some of them were identified through the group email list of physicians who normally attended the Thyroid Conference at the Vancouver Cancer Centre once a month. The rest of the physicians were contacted either through referral from a physician at the Vancouver Cancer Centre or from the staff members of the nuclear medicine department of the hospitals. While this method of sampling might not be able to include 100% of the physician population who were practicing in the areas of nuclear medicine, radiation oncology, endocrinology and surgery, it was the goal that at least one relevant physician from each of the five hospitals and four cancer centres in BC (see Introduction) was included in the subject pool. A letter that included an introduction of the research study and the website address of the online questionnaire was sent to the physicians via email, RIGHT fax or regular fax. In order to improve the response rate of the survey, a brief introduction of the research study was presented to a group of physicians who had attended the Thyroid Conference at the Vancouver Cancer Centre on May 1, 2003. Follow-up emails and faxes were sent to them a week prior to the deadline in attempt to obtain a higher response rate.
  7. 7. b) Questionnaire for Dietitians A convenience sample of 24 dietitians was included in this study. Local dietitians from each of the five hospitals in BC (see Introduction) were identified through their clinical nutrition managers or the staff members of the nuclear medicine department of the hospitals. These dietitians were either currently working in or have recently (< 2 years) worked in medicine, surgery or oncology inpatient and/or outpatient settings. Dietitians who have counseled patients with head or neck cancers at each of the four cancer centres in BC (see Introduction) were identified through the advisor of this research study (who was also a dietitian working at the Vancouver Cancer Centre). The remaining dietitians who were included in this study were working in other provinces across Canada. They were selected from the members list of the Oncology Network of Dietitians of Canada based upon their area of practice (e.g. medicine, surgery, head or neck oncology, and outpatient). Out-of-province dietitians (but not physicians) were included in this study due to the limited availability of BC dietitians who would see patients for a LID. Emails that contained an introduction of the research study and the website address of the online questionnaire were sent to the dietitians who were included in the study. Most of the dietitians were contacted via phone ahead of time in order to obtain their email addresses. Follow-up emails were sent out twice (seven days and three days) prior to the deadline of the questionnaire. All the data obtained from closed-end questions on the questionnaires were gathered and presented through descriptive statistics (e.g. mean, mode, and median).
  8. 8. For open-ended questions, comments were collated and compared with the recommendations made in current literature. Patient Diet Information In order to obtain a better insight of what diet information patients were informed prior to the I-131 scans and treatments, the nuclear medicine department of each of the five hospitals were contacted via phone. Brief and informal phone interviews were conducted with either the nuclear medicine supervisor or a physician in the department. Patient information handout(s) from each of the hospitals were also obtained from them via fax after the interviews. LITERATURE REVIEW Radioactive Iodine Therapy Radioactive Iodine 131 (I-131) is a special form of iodine that has been energized and used in the treatment of thyroid cancer. (13) Sixty years ago, Keston and his colleagues demonstrated that I-131 could be stored in a metastasis of well-differentiated thyroid adenocarcinoma. (5) Since then, this technique has been used to destroy residual thyroid tissue, or to treat recurrent disease or metastasis. (6) Although there are four main types of thyroid cancer, namely papillary, follicular, medullary, and anaplastic cancers, only papillary and follicular thyroid cancers can take up iodine. (6) In addition, only up to 50% of these tumors can absorb iodine in sufficient quantities to be therapeutically beneficial. (6) Generally, patients need to be off thyroxine (T4) for at least 4 weeks, and triiodothyronine (T3) for at least 2 weeks before an iodine scan or treatment. (6) This is because thyroid hormone withdrawal not only reduces body stores
  9. 9. of iodine, but also increases serum thyrotropin (TSH) production, resulting in an increased uptake of I-131 by thyroid tissues. (14, 15) On the day of the procedure, I-131 will be given as a pill or drink. (7) Depending on the hospital policy and patients’ living environment, patients might be required to stay in hospital for a few days before the radioactivity falls to safe levels. (6, 7, 24) High dose I-131 therapies can also be done on an outpatient basis, as long as it is judged by the Radiation Safety Officer and the Nuclear Medicine physician, that no significant radiation safety hazard will be exposed to any member of the public. (9) Scans are done as outpatients and do not require hospitalization. (6) Low-Iodine Diet As thyroid tumor cells have less avidity for iodine than normal thyroid cells, the administration of I-131 in the treatment of thyroid cancer is often compromised by its inherent nature of limited uptake. (10, 11) It is said that the magnitude of I-131 uptake by residual thyroid tumor cells is less than 10% of the administered radiation dose. (10) As well, the radiation dose can be negatively affected by the shorter effective half-life of I-131 in tumor cells compared with normal thyroid cells. (22) As a result, numerous studies over the past decades have been done to experiment on various methods (e.g. the establishment of high TSH levels by thyroid hormone withdrawal) that might be able to improve I-131 uptake in the treatment of thyroid cancer. (22) Although early studies have demonstrated that I-131 uptake can be increased when the body store is deficient in iodine (10), there have been very limited literature studies that have investigated the effectiveness of LID in the treatment of thyroid cancers. (22) The notion of using a diet low in iodine (in addition to diuretics) to induce
  10. 10. body iodine depletion first emerged in a study published in 1965. (12) Several other studies in the 60’s that have investigated the effectiveness of diuretics in the uptake of I-131 also put their subjects on a LID. Very different from the LIDs that are now in use, the earliest version of this diet resembled a fluid diet that consisted principally of low- iodine milk (treated with an anion exchange column, providing 2 ug instead of 12-13 ug / 100 ml), with free access to orange juice, distilled water, coffee, chocolate, and vanilla throughout the study. (10, 12) A LID that resembled the diets now in use by physicians and dietitians was found in a 1969 study. (11) In this study which was also primarily investigating the effectiveness of diuretics in the uptake of I-131, subjects were placed on a diet containing 20 to 25 ug of iodine daily for five days. (11) Differing from the LID adopted by the 1965 study, this diet consisted of a selection of foods such as lean beef or veal, lake trout, peas, cauliflower, fresh tomatoes, onions, cucumbers, lettuce, fresh apples, fresh pears, oranges, rice, boiled potatoes, milk (one or two glasses), water, coffee and chocolate. (11) One of the earliest studies on the actual LID was carried out by Goslings in 1975. In this study, he examined the effect of a LID on I-131 therapy by putting seven follicular thyroid carcinoma patients on a LID (30 ug iodine daily) for four days prior to the administration of I-131. (4) He found out that the mean urinary iodine excretion was reduced to about 25% of basal values, and that the diet might result in a two-fold increase in radiation dose to the tumor due to an increase in effective half life (t1/2). (4, 5) However, a combination of LID and ethacrynic acid administration did not seem to further decrease urinary iodine excretion. (4)
  11. 11. The next study was published in 1983 in which Maxon et al studied 40 patients between 1974 and 1982. (5) In this study, nineteen patients with well-differentiated thyroid adenocarcinoma were prescribed with a LID (1400 kcal; 45-50 ug iodine daily) without the use of osmotic diuresis a week prior to I-131 administration. (5) The remaining twenty-one patients with the same type of cancer were asked to follow their “regular” diet (RD). (5) Different from Goslings’ study, lists of allowed and restricted foods in each food category (i.e. vegetable, bread, fruit, meat, milk, milk products, fat and miscellaneous), along with suggested number of servings allowed for each food group and sample menus were included in the article. (5) Maxon et al found that the urinary iodine excretion levels of patients who were on the LID were significantly lower (i.e. 12% of basal values) than those who were on the regular diet. (5) They also supported Goslings’ finding that an appropriate LID might be useful in increasing the radiation dose per mCi of I-131 administered. (5) None of the patients who followed the LID experienced side effects such as nausea and diarrhea, but they did complain that the diet was “boring”. (5) It was concluded that a LID is a safe and potentially useful treatment to be used in conjunction with the I-131 ablative therapy of residual normal tissue. (5) However, there was no impact on metastatic thyroid lesions, which might be due to shorter retention time of iodine in metastatic tumor as compared with normal thyroid tissue. (5) While most if not all prior studies supported the effectiveness of the LID, the study conducted by Maruca and his colleagues in 1984 was one of the first studies that began to query the true effectiveness of the diet. The three patients who were included in this study were put on an Iodine Depletion Regimen (IDR), which consisted of a LID
  12. 12. (< 25 ug iodine daily), a diuretic (hydrochlorothiazide or furosimide), 12 g sodium chloride, and 3 litres of water, daily for 5 days. (1) Although the results of the study demonstrated that the IDR could significantly reduce total-body iodine and increase I-131 uptake into metastatic lesion of well-differentiated thyroid carcinoma, it might not be as effective as prior studies have suggested. (1) While the amount of I-131 taken up by tumor tissue had increased, the total-body radiation was elevated at the same time due to marked decrease in renal clearance of I-131 in response to vigorous diuresis. (1) Consequently, the increase in I-131 tumor uptake relative to the total body dose was not as much as the study might have first indicated. (1) As well, the use of diuretic did not deem to be useful for achieving iodine depletion, which was a finding similar to Goslings’ study. (1) In 1988, Lakshmanan et al developed a simplified LID for I-131 scanning and therapy of thyroid cancer. (8) In this study, five patients achieved a low-iodine intake (< 50 ug iodine daily) and reduced urinary iodine excretion (22% of basal values) by following a more simple-to-follow LID for 4 weeks preceding the I-131 test. (8) Instead of giving patients lists of alternate food for each food category, a LID that emphasized simplicity of diet instructions and maintenance of nutritionally balanced intakes was developed. (8) A set of written information was given to each patient after they had been instructed by a dietitian. (8) Generally, they were asked to check the label of all prepared foods for algae derivatives, all breads for iodates, and avoid all red colored foods and medicines. (8) As well, only the use of high iodine foods - iodized salt, sea salt, dairy products, eggs, seafood, and restaurant foods should be avoided. (8) Food products such as cakes and breads were allowed, despite that they might contain small
  13. 13. amounts of milk and eggs. (8) Differing from the diet proposed by Maxon et al, the specific type and amount of foods allowed in this LID were not indicated. As well, Lakshmanan and his colleagues seemed to allow various foods (e.g. cured and processed meats) that were restricted by Maxon et al. Apparently, Lakshmanan et al relied heavily on their patients in finding out and avoiding foods that could be high in iodine (e.g. vegetables canned in salt). This study, after taking into account of the earlier studies, concluded that one week of iodine restriction would be sufficient to significantly increase I-131 uptake. (8) However, it might be more effective if the patients could follow this diet 2 weeks prior to their I-131 scan and/or treatment. (8) It wasn’t until 2001 when the next study on LID was conducted. In this study, Morris and his colleagues re-evaluated the impact of a stringent LID on ablation rates in I-131 treatment of thyroid carcinoma. (3) Compared with earlier studies, this was a larger-scale retrospective study as 94 subjects were included in between 1990 and 1999. (3) Fifty regular diet (RD) patients were given simple verbal pre-ablation dietary instructions (i.e. avoid salt, multivitamin/mineral preparation that include iodine, and all seafood, including sushi, shellfish, and other fish) by a nuclear medicine technician via telephone. (3) Forty-four LID patients were given a copy of their diet instructions, either by mail or in person. (3) Similar to the diet proposed by Maxon et al, a list of allowed and restricted foods was provided. However, the actual amount of foods that were allowed in their LID was not specified. Regardless of their assigned diet regimen, all patients were asked to follow the diet for 10-14 days prior to therapy. (3) Similar to all previous studies, Morris et al found that the stringent LID reduced both dietary iodine intake and urinary iodine excretion. (3) This study also did not disprove the possibility
  14. 14. that a LID might allow patients to be treated with smaller dosages of I-131. (3) Differ from the predictions made by Goslings, Lakshmanan, Maxon and their colleagues on the impact of LID on treatment outcomes, the ablation rate in thyroid cancer patients following LID was numerically but not statistically greater than those following the regular diet in this study. (3) This might be due to the fact that all their patients received dietary instructions that reduced their iodine intake. (3) In addition, their sample size might not be large enough to show significantly different ablation rates between the two diets. (3) Several patients had provided valuable feedback regarding the palatability and facility of following the diet. (3) Some commented that the diet was difficult to understand and confusing. Others found it “overwhelming” to stay on the diet while adapting to a newly diagnosed cancer and withdrawing from medication. (3) Different from other LID studies, pre-ablation scanning was not conducted in this study because it was believed that the benefits of a scan would not outweigh the costs of additional radiation exposure, patient inconvenience, and concerns regarding the effect of the scan dose on I-131 uptake of a subsequent treatment dose. (3) It was concluded that a larger sample size is warranted in order to prove whether RDs or LIDs provide any significant improvement in ablation rates. (3) This was because a decrease in American dietary iodine intake might have affected the results of the study. (3) The most recent study on LID was published in April 2003 by Pluijmen et al. In this retrospective study, a group of patients with differentiated thyroid carcinoma were either put on a 4-day LID (n = 59) as defined by a maximal iodine urinary excretion of 49.4 ug / day or a standard diet (n = 61). (22) The uptake of I-131 in thyroid remnants during ablation and efficacy parameters of remnant ablation 6 months after the
  15. 15. procedure were compared between both diet groups. (22) It was found that the 24-hour urinary iodine excretion by LID during ablation was significantly reduced to an average of 27 ug / day. (22) This excretion level was comparable to previous studies done by Gosling, Maxon et al and Lakshmanan et al. (22) In addition, it was found that thyroid remnant uptake of I-131 was increased by 65% (P < 0.001) in the LID group. (22) Investigations on patients 6 months after ablation also showed that successful ablation was observed in a statistically significant number of patients who were put on the LID during ablation. (22) This study was one of the first that examined the impact of a LID on the efficacy of thyroid remnant ablation. It not only proved that a LID with a duration of 4 days* was sufficient to achieve iodine depletion, but concluded (for the first time) that a LID during thyroid remnant ablation could improve the efficacy in increasing thyroid remnant I-131 uptake. (22) It was suggested, at the end of the study, that it would be beneficial to investigate whether an LID during ablation can result in a better clinical outcome in the long term. (22) * EXCEPTION: All fish and sea products are not allowed from 1 week prior to I-131 administration. RESULTS Questionnaire for Physicians Of the 22 questionnaires sent to physicians, 8 of them were completed and returned (response rate: 36%). Despite the effort that was made to ensure that at least one physician from each of the five hospitals and four cancer centres (see introduction) were included in this study, it should be noted that some of the physicians from the
  16. 16. above facilities did not respond to the questionnaire. Therefore, the data summarized below might not represent the full picture of the current practices and perceptions of LID among physicians in all facilities that treated I-131 patients in BC. Among the eight physicians who responded to the questionnaire, four of them were working at the Vancouver Cancer Centre. One physician was working at the Fraser Valley Cancer Centre and three physicians were working at Vancouver General Hospital. Two physicians were working at St. Paul’s hospital and one physician was working at Surrey Memorial Hospital. It should, however, be noted that some physicians were working in more than one site. As for the areas of practice of these physicians, three of them were working in the area of nuclear medicine, while four of them were working in radiation oncology. Only one physician was from endocrinology. The number of years of experience in their areas of practice ranged from 3 to 24 years. Out of all eight physicians who responded to the questionnaire, all of them were aware that LIDs have been used in association with I-131 procedures. However, only six of them recommended the diet, while the remaining two did not think it was necessary. Among the physicians who recommended the diet (n = 6), half of them prescribed the diet for the procedures of I-131 scanning, ablation of thyroid remnants, and treatment of metastasis, while the other half only prescribed the diet for the latter two procedures. The number of days that patients were told to follow the diet varied among physicians with a range of 5 to 30 days (median: 10.5 days; mode: 14 days) before the procedure, and a range of 0 to 5 days (median: 3 days; mode: 3 days) after
  17. 17. the procedure. The total number of days that patients were recommended to stay on the diet by their physicians ranged from 8 to 30 days (median: 11.5 days, mode: 8 days). Other than the inconsistency in terms of the duration of the diet prescribed by physicians, the recommended level of iodine intake restriction also varied among them. Comments received included: “none set”, “no sushi”, “reduced iodine food intake”, “minimal restriction – mainly avoid iodine rich foods such as seafood” and “moderate restriction – do not recommend complete elimination of all iodine-containing foods, but significant restriction of diet (i.e. partial restriction of some items, complete elimination of others) e.g. ½ cup of milk OR 2 small slices of cheese. NO seafood, seaweed, and iodized salt, etc.” In particular, one physician stated “< 50 ug iodine / day,” despite that he further commented that he generally did not recommend a particular level of iodine in the diet. He explained that patients would normally have a diagnostic scan prior to the therapy. Only patients with unexpected findings on their diagnostic scans were questioned further with respect to diet and iodine containing medication or contrast. In terms of the route that recommendations were being delivered, one out of six physicians provided both verbal and written instructions while four of them provided verbal instructions only. The remaining physician provided patients with a handout of written instructions without reviewing it with them. This physician stated that he had other information regarding consent and radiation safety issues which he must review with the patients prior to the procedure. He admitted that he did not use the diet handout on every patient. He would only provide the handout to patients who asked for a diet to follow. The only physician who provided both verbal and written instructions also admitted that he rarely used a written sheet of instructions. However, he would definitely
  18. 18. give verbal instructions at the time of obtaining consent. This was because some patients might have been put on a LID previously by their radiation oncologists. One of the physicians who only provided verbal instructions stated that in the hospital where he was working in, there were no official LID handouts. The nuclear medicine supervisor of the same hospital also stated, during the informal phone interview, that patients were generally told to follow their “usual” diets. In spite of that, the physician personally believed that an official diet handout would be beneficial because he would give verbal diet instructions only when he remembered. This showed the inconsistencies in the physician’s perceptions on the efficacy of LID, the actual practices and the general departmental guidelines for patients receiving I-131 scans and treatments. As for the references of their written and/or verbal instructions, most of the physicians could not provide their source(s) of information that they (or the person who developed the handout) have used. However, one of the physicians did state that he had other information sources in addition to the hospital diet handout. These included previously published diets (e.g. the low-iodine diet at the University of Pennsylvania which he had helped drafted many years ago), and textbooks (e.g. a low-iodine diet was included in a textbook called Nuclear Medicine Therapy by John C Harbert). When the physicians were asked when was the last revision date of their written diet handouts, one of them stated “1-5 years ago” while the other one reported “>10 years ago”. This showed that the information provided on the handouts could be somewhat outdated. Figures 1 and 2 shows the type of written and verbal instructions that physicians generally provided to their patients.
  19. 19. FIGURE 1: Written instructions provided by physicians FIGURE 2: Verbal instructions provided by physicians 0 1 2 3 No Eggs No Dairy Products No Seafood No Restaurant Foods No Iodized Salt, Sea Salt No Food Containing Red Food Dyes No Breads Made With Iodate Dough Conditioners No Multivitamins Containing Iodine No Iodine-Containing Foods (but without giving specific examples to your patients) Use Multivitamin and Calcium Supplements Use Distilled Water Only WrittenInstructions Number of Physicians 0 1 2 3 4 5 No Eggs No Dairy Products No Seafood No Restaurant Foods No Iodized Salt, Sea Salt No Food Containing Red Food Dyes No Breads Made With Iodate Dough Conditioners No Multivitamins Containing Iodine No Iodine-Containing Foods (but without giving specific examples to your patients) Use Multivitamin and Calcium Supplements Use Distilled Water Only VerbalInstructions Number of Physicians
  20. 20. Only 2 out of 6 physicians have received feedbacks on their written and/or verbal LID instructions from their patients. One of these two physicians reported that the comments he had received included: “the diet was unpalatable”, “it was overwhelming to maintain the diet while adapting to a new diagnosis and withdrawing from medication”, and “it was difficult to adhere to the diet for the duration it was prescribed.” He also commented that the diet sheet from their own facility was confusing to some patients. The other physician reported that some of his patients have commented that the diet was inconvenient, but it was not difficult to follow. The personal beliefs regarding the efficacy of LID in relation to the overall I-131 procedures appeared to be very mixed among physicians. Only one physician truly believed that the diet was moderately important, while another physician commented that he was not sure how important a role the diet played. One physician believed that there was no evidence in literature to support its use, even though he would not discourage his patients if they wanted to follow the diet themselves. One of the physicians commented from his experiences that patients who had a high iodine diet prior to scanning would usually end up having an ineffective study. Therefore, rather than believing that a LID was necessary, he thought it would be more important to avoid high iodine foods. Another two physicians shared the same view stating that the diet might have minimal benefit except to avoid large intake. One physician commented that even though he was not sure about the actual benefits of the diet, it still seemed to be a good idea. However, he felt that it might be impractical to implement it, especially prior to the treatment. The final physician who has commented on the diet stated that the diet
  21. 21. might be marginally effective if iodine uptake was poor. However, he also felt that it would be very difficult for patients to adhere to the diet. Only 1 out of 6 physicians was currently referring his patients to a dietitian for LID counseling. However, 3 out of 6 physicians thought that it would be beneficial to refer their patients to a dietitian for LID counseling. One of the remaining three physicians felt that referral to a dietitian would probably not be necessary for most patients. However, he thought it would still be beneficial to have access to a dietitian’s help for some patients. Only one out of six physicians was not sure whether it would be beneficial to refer I-131 patients to a dietitian for LID counseling. For the two physicians who did not recommend a LID at the time of this questionnaire study, both of them agreed that they would still consider recommending it to their patients before AND after the I-131 procedures in the future. One of them said he would recommend the diet if the patient had a borderline uptake. The other commented he would certainly recommend the diet if there was clinical and published evidence to support it. Question Five on the questionnaire (i.e. “If you will consider recommending a low-iodine diet to your patients in the future, will you consider referring your patients to a dietitian for a low-iodine diet counseling as well?”) was misinterpreted by five physicians. It was originally a question for physicians who did not recommend a LID for I-131 procedure(s). Seven physicians (including the two physicians who truly did not recommend the diet) answered this question. Regardless, their answers to this question were still valuable and would therefore be included in the study. For the two physicians who originally did not recommend the diet to their patients, one of them was unsure
  22. 22. whether he/she would consider referring his/her patients to a dietitian. This physician said it would depend on the availability of pamphlets. Oppositely, the other physician, who also did not recommend the diet originally, said he/she would consider referring his/her patients to a dietitian should he/she decide to recommend the diet to his/her patients in the future. For the four physicians who did recommend the diet but were not referring their patients to a dietitian for LID counseling, two of them stated that they would consider referring patients to a dietitian in the future. However, it was further commented by one of these two physicians that only some patients could be referred because those diet instructions should happen at the level of clinicians (e.g. Radiation Oncologist). One of those four physicians was still unsure regarding patient referrals to a dietitian and said it would depend on how easy it would be to get patients seen by a dietitian. The remaining one physician who recommended the diet but was not referring patients to a dietitian did not misinterpret the question and was therefore not included here. For the physician who was originally referring patients to a dietitian for LID counseling, he/she stated that he/she would continue to do so. Similarly, the physician who was not referring patients to a dietitian originally would not consider referring patients to a dietitian in the future because it was commented as “excessive”. In the year 2002, the number of patients treated with I-131 procedures by these physicians varied from 2 to 50 patients. In particular, the three physicians who were working in nuclear medicine treated 25, 40 and 50 patients with I-131, respectively. Not surprisingly, the only endocrinologist who responded to the questionnaire treated the least number of patients with I-131 in 2002.
  23. 23. Questionnaire for Dietitians Of the 24 questionnaires sent to dietitians, 15 were completed and returned (response rate: 62.5%). Among the dietitians who responded to the questionnaire, ten of them were practicing in British Columbia, three were practicing in Ontario, one was practicing in Nova Scotia, and one was practicing in Manitoba. The areas of practice of these dietitians also varied significantly, which included: adult metabolic, medicine, surgery, oncology (inpatients and outpatients), and causal. The number of years that these dietitians have been practicing in their current areas of practice ranged anywhere from one to thirty years. Out of 15 dietitians who returned the questionnaire, seven of them (47%) had experience in counseling patients on a LID. Eight of them (53%) have never had an opportunity to counsel patients for this diet thus far. When they were asked about the kind of procedure(s) in which the diet was prescribed for, it appeared that the most common I-131 procedure was ablation of thyroid remnants. The second most common procedure was I-131 scanning and the third one was I-131 treatment of metastasis. One dietitian indicated that she was not sure if there was another reason for her patients to follow a LID. Six out of seven dietitians were able to recall the duration of diet prescribed by their patients’ physicians. Similar to the physicians’ responses, the duration of the prescribed diet ranged from 5 to 14 days (median: 10.5 days; mode: 14 days) before the procedure, and 0 to 2 days (median: 0 days; mode: 0 days) after the procedure. The total number of days before and after the procedure ranged from 5 to 16 days (median: 10.5 days; modes: 5 and 16 days).
  24. 24. Only 3 dietitians commented on the question regarding the level of iodine intake restriction that their patients have followed. Among the three of them, only one dietitian could clearly state that their LID provided approximately 50 – 60 ug of iodine daily. The other two dietitians said it was not indicated on the diet sheet, despite one who stated that it might possibly be 50 ug, while the other reported that it was only indicated as a “low” iodine diet. When the dietitians were asked how they provided patient education on LID, five of them reported that they provided patients with both verbal and written instructions. The remaining two dietitians commented that a diet handout that was written by dietitians would be given to all patients undergoing I-131 scans and ablative treatment by the Nuclear Medicine Department. The contact number of the dietitians would be printed on the diet sheet and patients could call them with questions. Similar comments were also observed in one of the five dietitians who provided both verbal and written instructions to patients. This dietitian commented that patient education on the LID was originally done by physicians or nurses in her facility. However, it has recently become the responsibility of nuclear medicine technicians. She only got called occasionally (e.g. 6 out of 30-40 patients seen by physicians or nurses in 2002). Different from the physicians, more dietitians were able to recall the source(s) of information of their written and verbal instructions. Despite one dietitian admitting that she was not sure about the source of information as their diet handout was developed by the dietitian before her, four other dietitians were able to locate the exact sources of information they have used. These references are shown in Table 1. For the remaining two dietitians, one stated that their current copy of the handout was simply a retyped
  25. 25. version of an old 1990s diet they had on file, while the other said that she was mainly using their old hospital diet handout, the diet handout of the adjoining cancer centre, as well as the diet manuals of various institutions. As for the sources of verbal instructions, they were basically the same as the written information because any verbal advices that the dietitians gave were to clarify the written materials that they have given to their patients. However, one dietitian commented that if the diet was too restrictive and difficult for patients to follow, she sometimes adopted the recommendation suggested by one of the latest LID studies (Morris et al 2001) and advised patients to avoid salt, seafood and multivitamins with iodine. Another dietitian commented that she would also ask for opinions from the dietitian at the adjoining cancer centre, in addition to the physician who ordered the diet. Three other dietitians commented that they might not be seeing all patients for individual counseling. This was because the oncologists would either provide their patients with verbal dietary advices and/or diet handouts with the dietitian’s contact information on it. Referral to a dietitian would only happen if the patient requested it. TABLE 1: References of published articles or unpublished materials that some dietitians have used during the development of their low-iodine diet handouts ______________________________________________________________________ Lakshmanan M, Schaffer A, et al. A Simplified Low-Iodine Diet in I-131 Scanning and Therapy of Thyroid Cancer. Clin Nucl Med 1988: 13: 866-868. Low-Iodine Recipe Collection with Guidelines and Suggestion for the Low-Iodine Diet. 2nd Edition. ThyCa: Thyroid Cancer Survivors’ Association, Inc. 2000. Maxon H.R., Thomas S.R., et al. Low Iodine Diet in I-131 Ablation of Thyroid Remnants. Clin Nucl Med 1983:8: 123-126. Morris L.F., Wilder M.S., et al. Reevaluation of the Impact of a Stringent Low-Iodine Diet on Ablation Rates in Radioiodine Treatment of Thyroid Carcinoma. Thyroid 2001; 11: 749-755. ______________________________________________________________________
  26. 26. When the dietitians were asked when their written instructions were last updated, only one dietitian reported that it was updated less than a year ago. Four of them stated it was 1 to 5 years ago and the remaining two stated it was 5 to 10 years ago since their diet handouts were last updated. Figures 3 and 4 shows the type of written and verbal instructions that dietitians provided to their patients. Table 2 shows some additional written instructions that individual dietitians gave to their patients. FIGURE 3: Written instructions provided by dietitians 0 1 2 3 4 5 6 7 No Eggs No Dairy Products No Seafood No Restaurant Foods No Iodized Salt, Sea Salt No Food Containing Red Food Dyes No Breads Made With Iodate Dough Conditioners No Multivitamins Containing Iodine No Iodine-Containing Foods (but without giving specific examples to your patients) Use Multivitamin and Calcium Supplements Use Distilled Water Only WrittenInstructions Number of Dieticians
  27. 27. FIGURE 4: Verbal instructions provided by dietitians Note: This bar graph does not truly reflect the type of verbal instructions provided by dietitians. This is because most dietitians who provided verbal instructions on LID did not answer this question on the questionnaire. TABLE 2: Additional written instructions provided by individual dietitians ______________________________________________________________________ 1. Allow ¼ cup whipped cream per day but no other dairy products 2. Limit dairy to milk (up to ½ daily), cream cheese and low-salt cheddar cheese 3. Avoid chocolate (for its milk content) 4. Avoid molasses 5. Avoid soy products 6. No salt water fish 7. Limit eggs to 3 per week 8. City water is OK but not well water ______________________________________________________________________ Of seven dietitians who have counseled patients on LID, all of them have received feedback on the written and/or verbal instructions of the diet from their patients. The most common complaint from patients was the difficulty in adhering to the diet for the duration it was prescribed. Other comments such as “the diet was confusing 0 1 2 No Eggs No Dairy Products No Seafood No Restaurant Foods No Iodized Salt, Sea Salt No Food Containing Red Food Dyes No Breads Made With Iodate Dough Conditioners No Multivitamins Containing Iodine No Iodine-Containing Foods (but without giving specific examples to your patients) Use Multivitamin and Calcium Supplements Use Distilled Water Only VerbalInstructions Number of Dietitians
  28. 28. and difficult to understand”, “the diet was unpalatable”, and “it was overwhelming to maintain the diet while adapting to a new diagnosis of cancer and withdrawing from medications” were the next most common complaints dietitians often received. A variety of other feedbacks were also reported by dietitians in the returned questionnaires. For instance, a dietitian reported that her patients often had some difficulties understanding that this diet is not salt-free. In addition, her patients complained that they consistently felt hungry and tired when they were following the LID. Similar comments were also received from another two dietitians. One of them commented that her patients were anxious about the diet because it caused weight loss and weakness. The other dietitian felt the same way and said the diet was more difficult for diabetics or young people with a big appetite. Aside from complaints, different questions were also raised by patients. These questions were often brought up by patients to clarify what foods specifically they should select. Examples of questions included: “What kind of juices can I drink?”, “What kind of low-salt cheese is OK?”, “Where can I get appropriate bread?” Despite most feedback from patients were generally negative, a few positive comments were also noted. For instance, a dietitian noted that the most common comment she had received was being given a very detailed food list was very useful, instead of having to use general guidelines and read every food label. Another dietitian recalled one of her patients saying that for the short period that he needed to stay on the diet, it was not a problem. Surprisingly, a dietitian in Nova Scotia commented that some of her patients were so concerned about optimizing I-131 scans and/or treatments that they actually
  29. 29. wanted to comply with a more rigid diet because they believed that it must be better to follow a strict LID. Similar to the physicians, the personal belief regarding the efficacy of LID in relation to the overall I-131 procedure(s) was a mixture of different point of views. Although a few dietitians commented that they had no opinions or knowledge on the diet because they have not seen any of these patients, they actually brought up a few important points. Their comments revealed that in some hospitals: 1. This diet is not ordered routinely for inpatients, or 2. It is not a standard practice for dietitians to see patients for a LID because diet instructions are usually provided by physicians or other health professionals, or 3. No such diet is actually implemented in the facility or included in the general guidelines for patients undergoing I-131 procedure(s) Several of these dietitians who have not seen any LID patients have also made some other important comments. For instance, a dietitian in BC felt that she had an impression that there was no evidence to support the efficacy of a LID for patients receiving I-131 procedure(s), despite the fact that she admitted she did not know this diet in great detail. Another dietitian in BC commented that she believed the restricted diet prior to the treatment would be fairly easy for patients to adhere to, and that it would be important for them to follow. However, she also further commented that inpatient dietitians in her facility do not counsel patients for a LID. Finally, a dietitian in Manitoba stated that a LID is still in use in the inpatient setting of their region. However, she has not had an opportunity to see these patients because she only works for outpatients.
  30. 30. She believed that when the diet was reviewed for the region, the physician was the one who was advocating for its inclusion in the regional diet compendium. For those who have had experience counseling patients on this diet, their attitudes towards it also varied. A dietitian in Ontario commented that she personally does not know if the diet is necessary or not. But if the physician is requesting it, she will then instruct the patient on it. Another dietitian, also in Ontario, had a similar comment. She said, even though she has not researched on this topic very much, the oncologist in their facility advises patients to stay on a LID, as this is recommended by the physicians and the team at the health sciences centre where their patients are sent. The third dietitian from Ontario who also counsels patients for a LID strongly believed that it is a diet valuable to adhere to. However, she felt that both excellent educational material and referral to dietitians are essential, and this is especially true if the patients are consuming ethnic foods. Back in BC, one of the dietitians here thought that a LID is helpful for I-131 treatment. However, she also felt that it would be necessary to find a balance between the benefits and patients’ ability to comply. More importantly, she truly believed that physicians and dietitians should be consistent in their dietary advice to avoid confusion. A dietitian on Vancouver Island said she was not sure about the true efficacy of the diet because the literature review thus far is inconclusive. As well, she said the information provided by the “Thyroid-Cancer.net” from the Johns Hopkins Thyroid Tumor Centre website and the Thyca: Thyroid Cancer Survivors’ Association Inc. website is different from each other and their hospital’s recommendations. Although she found the information very confusing, she would still be very interested in updating their information material. She was also interested in finding out how strict a LID should
  31. 31. be. She thought it would still be a good idea to limit the diet iodine in case it does help treatment until proven otherwise. The same was felt by a dietitian in Nova Scotia, who also was not sure how strict the diet needs to be. While she thought literature supports the concept of starving cells of iodine to increase uptake for scan and/or ablative treatment, she would favour a less stringent diet if it is efficacious. Among the seven dietitians who have counseled patients on LID, the number of these patients whom they saw in the year 2002 ranged from 1 to 30 cases. In particular, five of these dietitians counseled 1 to 6 patient(s) on LID last year, while the remaining two dietitians counseled 30 patients on LID within the same period of time. The geographical locations where more patients were relatively seen by dietitians for LID counseling or telephone enquiries included Victoria, British Columbia and Toronto, Ontario. Patient Diet Information a) Patient General Diet Information Tables 3A to 3G summarize the general diet information patients would normally receive prior to I-131 procedure(s). It includes the information provided by each of the five hospitals in BC that offer I-131 scans and treatments. It also includes the diet information from Vancouver Cancer Centre, the only cancer centre in BC that has its own handout on LID. Diet information from two other hospitals in Ontario (ON) and Nova Scotia (NS) were also included in this study to provide insight of what out-of- province hospitals would recommend in terms of the use of LID in the treatment of thyroid cancer.
  32. 32. It should be noted that the following table only summarizes the diet instructions provided by each hospital’s official diet and/or patient information handout(s). Individual practitioners (e.g. physicians, nurses, and dietitians) might have their own handouts and/or information sources that they would use during patient counseling. TABLE 3A: Patient general diet information provided by Vancouver General Hospital Name of Hospital Availability of a LID Handout Duration of Diet Availability of a List of “Food Allowed” and “Foods to Avoid” Additional Diet/Nutrition Information Provided Number of Food Groups Divided Sample Menu Provided Date of Last Revision The Type of Procedure that the Diet is Prescribed For As Stated on the Handout Vancouver General Hospital (BC) YES - A two- page handout on LID is available - Primarily given out by physicians or staff members at the Nuclear Medicine Department - The diet should be consumed for 2 weeks prior to the first treatment YES - See Table 4 and 5 YES - Avoid restaurant foods due to the unknown amount of iodized salt used - Avoid OTC medications such as cough syrups that may contain iodine compounds - Daily calcium supplementation with 1200 mg calcium carbonate is recommended 8 Food Groups - Dairy - Protein (meat) - Fish - Grains/ Starches - Fruits - Vegetables - Misc.* - Snack Foods - For the “Fish group”, it is highlighted that “none is allowed” and that it is the most important food to avoid NO Unknow n ~ 1-5 years ago - The type of procedure that the diet is prescribed for is not stated on the handout - The rationale for following the diet is provided by stating that it is “for optimum results” *Misc. = Miscellaneous
  33. 33. TABLE 3B: Patient general diet information provided by St. Paul’s Hospital Name of Hospital Availability of a LID Handout Duration of Diet Availability of a List of “Food Allowed” and “Foods to Avoid” Additional Diet/Nutritio n Information Provided Number of Food Groups Divided Sample Menu Provided Date of Last Revision The Type of Procedure that the Diet is Prescribed For As Stated on the Handout St. Paul’s Hospital (BC) NO - LID (or any form of diet restriction) is not mentioned on the handout of general guidelines - A regular diet is generally ordered for inpatients unless the concurrence of other health conditions (information is based on the informal phone interview) - Out - patients are told verbally that they can follow their usual diets (information is based on the informal phone interview) N/A NO NO NONE NO N/A N/A
  34. 34. TABLE 3C: Patient general diet information provided by Surrey Memorial Hospital and Kelowna General Hospital Name of Hospital Availability of a LID Handout Duration of Diet Availability of a List of “Food Allowed” and “Foods to Avoid” Additional Diet/Nutrition Information Provided Number of Food Groups Divided Sample Menu Provided Date of Last Revision The Type of Procedure that the Diet is Prescribed For As Stated on the Handout Surrey Memorial Hospital (BC) NO - LID (or any form of diet restriction) is not mentioned on the handout of general guidelines N/A NO YES - Patients should drink plenty of fluids for 3 days following the I-131 thyroid therapy to help I-131 leave the body more rapidly NONE NO N/A N/A Kelowna General Hospital (BC) NO - A handout on general guidelines is given to patients prior to the treatment. It mentions a few food items that need to be avoided - Vitamins containing iodine: 3-4 weeks - Health foods (kelp/lecithin): 3-4 week - Diet foods containing kelp/lecithin: 3-4 weeks YES - Only a few foods that need to be avoided is available - See Tables 4 and 5 YES - Patients should drink plenty of liquids (starting 90 minutes after the dose of I-131) for either 1 day (I-131 Therapy < 1100 MBq) or 3 days (I-131 Therapy > 1100 MBq) NONE NO N/A - For patients who will receive thyroid uptake & scan and thyroid treatment - The rationale for following the diet instructions is somewhat explained by stating that these are the preps for the procedure TABLE 3D: Patient general diet information provided by Royal Jubilee Hospital
  35. 35. Name of Hospital Availability of a LID Handout Duration of Diet Availability of a List of “Food Allowed” and “Foods to Avoid” Additional Diet/Nutritio n Information Provided Number of Food Groups Divided Sample Menu Provided Date of Last Revision The Type of Procedure that the Diet is Prescribed For As Stated on the Handout Royal Jubilee Hospital (BC) YES - A ten-page handout on LID is available - Can be given out by physicians, staff members at the Nuclear Medicine department, or the medical / oncology dietitian - The diet should be consumed for 5 days prior to the treatment - Inpatients should stay on the diet during the course of hospitalization - The diet can be discontinued once the treatment is completed and/or the patient is discharged home YES - See Table 4 and 5 - Foods must be prepared without salt because table salt has iodine added - Pickling salt can be ground up and used in place of table salt - Salt substitutes and sea salt must be avoided - A minimum of 12 cups of water must be consumed daily - Distilled water must be used if well or other water of unknown iodine content is used – tap water is OK because Victoria city water has a low-iodine content - Do not eat commercially prepared food that contains food coloring, agar, sodium alginate or carrageenin 7 Food Groups - Meat & Alternates - Breads & Cereals - Fruits - Vegetables - Dairy Products - Fats - Misc. * YES - Sample menus for breakfasts, lunches and suppers are provided Nov 1999 - For patients who need to receive I-131 - Actual procedure(s) that the diet is prescribed for is/are not indicated on the handout - The rationale for following the diet is briefly explained at the beginning of the handout. It is stated that “Prior to receiving radioactive iodine, you must deplete your body of iodine. This is achieved by consuming a diet low in iodine” *Misc. = Miscellaneous TABLE 3D (continued): Patient general diet information provided by Royal Jubilee Hospital
  36. 36. Name of Hospital Availability of a LID Handout Duration of Diet Availability of a List of “Food Allowed” and “Foods to Avoid” Additional Diet/Nutrition Information Provided Number of Food Groups Divided Sample Menu Provided Date of Last Revision The Type of Procedure that the Diet is Prescribed For As Stated on the Handout Royal Jubilee Hospital (BC) (continued) - Nine low- iodine recipes (3 entrees, 3 desserts, plus rice, salad & salad dressing) - A list of local bakeries that supply salt- free, iodine- free bread - Avoid cough syrups that may contain iodine compounds TABLE 3E: Patient general diet information provided by Vancouver Cancer Centre
  37. 37. Name of Hospital Availability of a LID Handout Duration of Diet Availability of a List of “Food Allowed” and “Foods to Avoid” Additional Diet/Nutrition Information Provided Number of Food Groups Divided Sample Menu Provided Date of Last Revision The Type of Procedure that the Diet is Prescribed For As Stated on the Handout Vancouver Cancer Centre (BC) YES - A six-page LID handout is available - Primarily given out by the head/neck outpatient nutrition oncology dietitian - The diet must be consumed for 5 days prior to and during the treatment YES - The maximum number of servings is stated for each food group - Serving sizes are also noted - See Table 4 and 5 - 12 cups of distilled water should be consumed daily - Distilled water must be used in preparing foods, including tea and coffee - If the patient is advised by his/her doctor that additional sodium chloride needs to be taken to aid in depleting the body’s iodine, taking the salt tablets three times a day with meals is recommended 7 Food Groups - Meat & Alternates - Breads & Cereals - Fruits - Vegetables - Dairy Products - Fats - Misc. * YES - A one- day sample menu with 3 meals and 3 snacks is provided February 1995 - For patients who need to increase their thyroid uptake of I-131 - Actual procedure(s) that the diet is prescribed for is/are not indicated on the handout - The rationale for following the diet is briefly explained at the beginning of the handout. It is stated that “the low iodine diet results in body iodine depletion so that thyroid uptake of radioactive iodine will increase” * Misc. = Miscellaneous TABLE 3F: Patient general diet information provided by Kingston General Hospital Name of Availability Duration Availability Additional Number Sample Date of The Type
  38. 38. Hospital of a LID Handout of Diet of a List of “Food Allowed” and “Foods to Avoid” Diet/Nutrition Information Provided of Food Groups Divided Menu Provided Last Revision of Procedure that the Diet is Prescribed For As Stated on the Handout Kingston General Hospital (ON) YES - A one- page LID handout is available - Another handout on general guidelines also contains some diet instructions - Given out by physicians or staff members at the Nuclear Medicine Department - Restrict iodine intake for the 6 weeks before the scan (i.e. avoid seafood and iodized table salt; use non- iodized salt) - Follow the LID for a week before receiving the I-131 - Continue the diet until the scan is completed - If I-131 is used for treating thyroid cancer, the diet should be continued for a week after the treatment YES - Mainly a list of iodine- containing foods to be avoided with additional comments such as “Fresh or frozen are OK” beside foods that need to be avoided - See Table 4 and 5 NO NONE NO Unknown - The diet is prescribed for patients who need to receive whole body radioiodine scan - The rationale for following the diet is explained briefly at the beginning of the handout. It is stated that “Foods and medications that contain iodine may interfere with the procedure that is planned for you. We would like you to stop eating any of the iodine- containing foods listed below…” TABLE 3G: Patient general diet information provided by Queen Elizabeth II Health Sciences Centre
  39. 39. Name of Hospital Availability of a LID Handout Duration of Diet Availability of a List of “Food Allowed” and “Foods to Avoid” Additional Diet/Nutritio n Information Provided Number of Food Groups Divided Sample Menu Provided Date of Last Revision The Type of Procedure that the Diet is Prescribed For As Stated on the Handout Queen Elizabeth II Health Sciences Centre (NS) YES - A one- page LID handout is available - It was primarily given out by physicians or nurses - It has recently been incorporated into an education booklet provided by a nuclear medicine therapist - Number of days prior to the treatment that patients need to follow the diet is not stated on the handout - It is however stated that a normal diet can be resumed on DAY 3 following the treatment YES - Mainly a list of foods that need to be avoided - A brief sentence on what foods can be consumed is also provided at the end of the handout. This includes non-iodized salt, food prepared from fresh meat or poultry, fresh or frozen vegetables, and fresh fruit - See Table 4 and 5 NO 3+ Food Groups - Fresh meat or poultry - Fresh or frozen vegetables - Fresh fruit - A list of unclassified foods that need to be avoided NO Unknow n - The diet is prescribed for patients who need to receive whole body radioiodine survey or thyroid ablation treatment - The rationale for following the diet is explained in detail at the beginning of the handout. See ** below ** In preparation for your Whole Body Radioiodine survey or thyroid ablation treatment, you are advised to limit, and preferably avoid, the following foods that are known to be high in iodine. We like to have your body very low in iodine so we can get the maximum benefit from the survey scan and/or treatment. Natural iodine competes with radioiodine because your body cannot tell the difference between the two. The less “natural” iodine you have in your body the more we will be able to see with the radioiodine.
  40. 40. In summary, it is apparent that not every facility is providing information on LID (or any form of diet) to patients receiving I-131 scans and/or treatments. Among the facilities which do provide diet information, their instructions are also very different. The recommendations provided by a facility might not necessarily be recommended by another facility. The followings are some of the examples in which different standards have been observed in different facilities. o Duration of diet o Use and avoidance of certain supplementations o List of avoided and/or allowed foods o Level of iodine intake restriction o Inclusion of different food groups o Inclusion of sample menus o Use of distilled water o Number of servings and serving sizes – Vancouver Cancer Centre is the only facility in this study that provides specific number of servings and serving sizes for each food category. The number of servings allowed for some food categories is much lower than the Canada’s Food Guide (e.g. only 2 servings of breads and cereals are allowed daily) In addition to the instructions that are different among facilities, the following aspects are also different as well: o The amount of information provided varied from a few lines to 10 pages o The written information were provided by different health professionals (e.g. physician, nurse, nuclear medicine technician, and dietitian)
  41. 41. b) Food Allowed The following table (Table 4) summarizes the foods that are allowed in a LID as indicated on the diet and/or general guideline handout(s) of each facility. St. Paul’s and Surrey Memorial Hospitals are not included because they do not provide any specific diet instructions. The handout provided by Kelowna General Hospital does not include information on the type of foods that are allowed in the diet and therefore, is not included in this table. TABLE 4: A comparison table that shows what foods are allowed in the LIDs of 5 facilities Food Group Food Item Vancouver General Hospital Royal Jubilee Hospital Vancouver Cancer Centre* Kingston General Hospital Queen Elizabeth II Health Sciences Centre Meat & Alternates Beef x (small portion and fresh only) x x x (fresh only) Eggs x (up to 3 eggs per week) Fresh Water Fish x x Lamb x x x (fresh only) Pork x (small portion and fresh only) x x (fresh only) x (fresh only) Poultry x (small portion and fresh only) x x (fresh only) Salt-free Peanut Butter x x x Veal x (small portion and fresh only) x x x (fresh only) Breads, Cereals, & Grains Barley x Bread without iodate dough conditioner x x (white, rye, wheat) Breads from local bakery x Cracked Wheat x Cream of Wheat x x
  42. 42. TABLE 4 (continued): A comparison table that shows what foods are allowed in the LIDs of 5 facilities Food Group Food Item Vancouver General Hospital Royal Jubilee Hospital Vancouver Cancer Centre* Kingston General Hospital Queen Elizabeth II Health Sciences Centre Breads, Cereals, & Grains (con’d) Noodles x Oatmeal x x Puffed Rice x x Puffed Wheat Cereals x x Red River x Regular Bread X (1-2 slices/day) Rice (prepared without salt) x (homemade) x x Rye x Salt-free Bread x Shredded Wheat x Spaghetti x (no salt/eggs) x x (egg-free) Sunny Boy x Whole Wheat x Dairy Products Cream Cheese x Cream or Whipping Cream x Low-Salt Cheddar Cheese x Milk x (up to ½ cup per day) x (up to ½ cup per day) x (small amounts in coffee and on cereal are OK) Fruits All Fresh Fruit Juices (bottles or cartons of natural fruit juice allowed) x
  43. 43. TABLE 4 (continued): A comparison table that shows what foods are allowed in the LIDs of 5 facilities Food Group Food Item Vancouver General Hospital Royal Jubilee Hospital Vancouver Cancer Centre* Kingston General Hospital Queen Elizabeth II Health Sciences Centre Fruits (con’d) Fresh and Frozen Fruits Only x Fresh Fruits Only x x Fresh, frozen, or Canned (drained) fruits x x (unless otherwise stated – see Table 5 and below) - Apple x x (fresh only) - Apricots x x (fresh only) - Avocados x x - Bananas x - Berries x x - Cherries x x (fresh only) - Cranberries x x - Figs x x (fresh only) - Grapefruits x x - Grapes x x - Mango x x - Melon x x - Nectarine x x - Orange x x - Peach x x (fresh only) - Pear x - Pineapple x x (canned only) - Plum x - Tangerine x Apple Juice x x Grape Juice x x Grapefruit Juice x x Lemon Juice x x Orange Juice x x Pineapple Juice x x
  44. 44. TABLE 4 (continued): A comparison table that shows what foods are allowed in the LIDs of 5 facilities Food Group Food Item Vancouver General Hospital Royal Jubilee Hospital Vancouver Cancer Centre* Kingston General Hospital Queen Elizabeth II Health Sciences Centre Vegetables Fresh or Frozen Vegetables Only x x Fresh Vegetables Only x (except spinach) Fresh, Frozen, or Low-Salt Canned (drained) Vegetables x x (unless otherwise stated – see Table 5 or below) - Asparagus x x - Beets x x - Broccoli x (fresh only) x (fresh only) - Brussel Sprouts x x - Cabbage x x - Carrots x x - Cauliflowers x x - Corn x x - Cucumber x x - Eggplant x x - Green Peppers x x - Lettuce x x - Lima Beans x (fresh or canned) x (fresh or canned) - Mustard Greens x x - Onions x - Peas x (Fresh or canned only) x (Fresh or canned only) - Potatoes x (fresh only; no skin) x x (fresh only) - Radishes x x - Rutabaga x x - Spinach x x - Squash x x (fresh only) - String Beans x x
  45. 45. - Tomatoes x x TABLE 4 (continued): A comparison table that shows what foods are allowed in the LIDs of 5 facilities Food Group Food Item Vancouver General Hospital Royal Jubilee Hospital Vancouver Cancer Centre* Kingston General Hospital Queen Elizabeth II Health Sciences Centre Vegetables (con’d) - Turnips x x - Mushrooms x x Fat Homemade Gravy without salt x x Homemade Oil and Vinegar Dressing x Oil x (vegetable or olive oil) x x Unsalted Margarine / Butter x x Vegetable Shortening x Miscellaneous Brewed Coffee x (brewed coffee or steeped tea – maximum 2 cups daily) x (brewed coffee or steeped tea – maximum 2 cups daily) Cashew Nuts x Garlic Powder x Gelatin x Gum Drop (not red) x Herbs x (fresh) x Jams & Jellies made with allowed fruits x Maple Syrup x x Marshmallows x x Multivitamin (iodine-free) x x x x Natural Honey x Non-Iodized Salt x x x x Onion Powder x Peanuts x Percolator or Drop Coffee x Pickling Salt x
  46. 46. TABLE 4 (continued): A comparison table that shows what foods are allowed in the LIDs of 5 facilities Food Group Food Item Vancouver General Hospital Royal Jubilee Hospital Vancouver Cancer Centre* Kingston General Hospital Queen Elizabeth II Health Sciences Centre Miscellaneous (con’d) Popcorn x (popped with vegetable or olive oil) x Rice Cakes (no salt added) x Spices x Splenda x Steeped Tea x (brewed coffee or steeped tea – maximum 2 cups daily) x (brewed coffee or steeped tea – maximum 2 cups daily) Sugar x x Unsalted Almonds x Vinegar x Walnuts x * NOTE: The number of servings for each food category, as well as the serving sizes allowed for each food item are specified on the LID handout of the Vancouver Cancer Centre. c) Foods to Avoid The following table (Table 5) summarizes all the foods that need to be avoided as indicated on the diet and/or general guideline handout(s) of each facility. St. Paul’s and Surrey Memorial Hospitals do not provide specific diet instructions and therefore, are not included in this table. TABLE 5: A comparison table that shows what foods should be avoided as indicated on the LID handouts of 6 facilities Food Group Food Item Vancouver General Hospital Kelowna General Hospital Royal Jubilee Hospital Vancouver Cancer Centre Kingston General Hospital Queen Elizabeth II Health Sciences Centre Meat & Alternates Canned Tuna x Canned, dried, salted or cured meats (ham, bacon, luncheon x x x x (+ spicy meat)
  47. 47. meats, sausages, frankfurters) TABLE 5 (continued): A comparison table that shows what foods should be avoided as indicated on the LID handouts of 6 facilities Food Group Food Item Vancouver General Hospital Kelowna General Hospital Royal Jubilee Hospital Vancouver Cancer Centre Kingston General Hospital Queen Elizabeth II Health Sciences Centre Meat & Alternates (con’d) Eggs x x (foods containing a small amount of eggs are OK) Fish in General x x Organ Meats x Poultry x Salted Peanut Butter x x x Sardines x Seafood in General x x Seawater Fish x x Shellfish x x x Breads, Cereals, & Grains All cereals and starch foods not listed under the corresponding “food allowed” list (see Table 4) x x Cookies x Packaged/enriched Rice Mixes x x Pastry x Dairy Products Cheese x x (cream cheese and low-salt cheddar cheese are allowed) x x x Cottage Cheese x x x x x Eggnog x x x Evaporated Milk x x x x x Ice-cream x x x x x Milk x (up to ½ cup daily) x (up to ½ cup daily) x x (small amount of milk in coffee or on cereal x (foods containing a small amount of milk are
  48. 48. only) OK) TABLE 5 (continued): A comparison table that shows what foods should be avoided as indicated on the LID handouts of 6 facilities Food Group Food Item Vancouver General Hospital Kelowna General Hospital Royal Jubilee Hospital Vancouver Cancer Centre Kingston General Hospital Queen Elizabeth II Health Sciences Centre Dairy Products (con’d) Pudding x x x x Sour Cream x x x Yogurt x x x x x Fruits All fruits not listed under the corresponding “food allowed” list (see Table 4) x x Banana x Canned Fruit Juices x Canned Fruits x x Dried Fruits x x x Hi-C x Tangerine x Vegetables All frozen vegetables x All vegetables not listed under the corresponding “food allowed” list (see Table 4) x x All vegetables, vegetable juices and soups canned with salt x x x x Canned Tomato / Pasta Sauce x Celery x Frozen / Canned Broccoli x x Frozen / Canned Spinach x Frozen Lima Beans x x Frozen Peas x x Pickles x x Sauerkraut x x Seaweed / Kelp / Lecithin or Food containing these x x x
  49. 49. ingredients TABLE 5 (continued): A comparison table that shows what foods should be avoided as indicated on the LID handouts of 6 facilities Food Group Food Item Vancouver General Hospital Kelowna General Hospital Royal Jubilee Hospital Vancouver Cancer Centre Kingston General Hospital Queen Elizabeth II Health Sciences Centre Vegetables (con’) Spinach (all forms) x Vegetables with sauces x Fat Commercial Gravy Mixes x Commercial Salad Dressing x x x Lard x x Regular / Butter Margarine x x x Miscellaneous Bouillon Cubes x x x Candy x Canned Soup x Carnation Instant Breakfast x Carnation Slender Bars x Celery Salt x Chili Sauce x x x Chocolate x Cocoa Mix x Corn Chips x Crackers x x Fast Foods x Figurine Diet Bars x Food Supplements x Garlic Salt x x Instant Coffee x x x Instant Tea x x x Ketchup x x x Lemonade x Meat Tenderizers x Molasses x x Multivitamin containing x x x x x x
  50. 50. iodine Mustard x x x TABLE 5 (continued): A comparison table that shows what foods should be avoided as indicated on the LID handouts of 6 facilities Food Group Food Item Vancouver General Hospital Kelowna General Hospital Royal Jubilee Hospital Vancouver Cancer Centre Kingston General Hospital Queen Elizabeth II Health Sciences Centre Miscellaneous (con’d) Nuts x x Olives x x Onion Salt x x Oriental Foods x Pizza x Pretzels x x Red Food Coloring x x x x Relish x Restaurant Foods x x Salt Substitute x Salted Chips x x Salty Foods x Sea Salt x x Seasoned Salts x x Soy Products (e.g. soy milk, tofu) x Soya Sauce x x Table Salt x x x x x Water (tap / well) x x (local tap water OK) x In summary, one could see that there were very few food items that are consistently allowed or not allowed in the LIDs of different facilities. This was solid evidence showing the discrepancies in terms of the food contents of a LID among facilities.
  51. 51. DISCUSSION To date, existing literature have all demonstrated a positive relationship between I-131 uptake in the thyroid and dietary iodine consumption. (1, 3, 4, 5, 8, 22) Among earlier studies, low-iodine diets (typically providing 30 - 50 ug iodine daily) were usually prescribed for between 4 and 14 days. (4, 5, 8) This not only significantly reduced urinary iodine excretion levels, but also resulted in increasing radiation dose to the tumor in patients with thyroid cancer by as much as two-fold. (4, 5, 8) Although there have been very limited studies that have investigated the efficacy of LID over the past few decades, a study published by Morris et al in 2001 has suggested that a less stringent diet that simply avoids high-iodine-containing foods might result in equivalent outcomes. (3) As well, a recently published study has finally demonstrated that a 4-day LID during I-131 remnant ablation is sufficient to improve the efficacy of the treatment. (22) Despite the establishment of a direct link between LIDs and improved ablation rates, it should be noted that this relationship has only been demonstrated in one study thus far. More studies that yield the same clinical outcomes might be needed to truly confirm the effects of the diet. This is because the study conducted by Maruca et al has suggested that LID might not be as effective as other studies have concluded. (1) The rationale behind this conclusion was that the increased I-131 uptake and retention by tumor tissues might not be increased significantly enough to increase the irradiation of well-differentiated thyroid cancer. (1) This was because the increase in lesion irradiation was also associated with an increase in total body radiation, a result of reduced renal clearance of I-131. (1) Therefore, before the true impact of LID on ablation rate can be
  52. 52. demonstrated by more studies, more research on their relationship is still warranted. (3) In the mean time, Morris et al suggested that it should be a routine to prescribe a LID prior to I-131 treatment because of its potential positive effect and little cost. (3) However, the diet should be more liberalized because a stringent diet could have potential ill effects on the psychological well being of newly diagnosed cancer patients. (3) Also, it might not be realistic to ask patients to follow a stringent diet for the duration it was prescribed. (3) As suggested by Pluijmen et al, a LID with a duration of 4 days is sufficient to deplete body iodine pool. (22) Last but not least, Morris et al mentioned in their study that they are currently studying a revised LID that requires patients to avoid salt, dairy products, processed bread, vitamin preparations containing iodine, and seafood. (3) Apparently, the practices and perceptions of LID varied significantly between facilities, or even between physicians and dietitians within the same facility. Despite all the physicians who responded to the questionnaire were aware that LIDs have been used in association with I-131 procedures, not all of them actually recommended it. As well, among the physicians who recommended the diet, I-131 scanning was a procedure in which a LID was not universally prescribed. The duration of LID prescribed by physicians also varied significantly. Based on the questionnaires returned by physicians, the duration of the diet ranged from 8 to 30 days, which was quite different from what literatures have suggested. However, it should be noted that for the physician who was prescribing a 30-day-diet, the level of iodine restriction was only minimal (e.g. patients were mainly told to avoid iodine rich foods such as seafoods). Interestingly, the duration of diet was only 5 to 16 days based on the returned
  53. 53. questionnaires from dietitians. This was somewhat closer to what literatures have recommended. In addition to the inconsistency in terms of the duration of the diet prescribed by different physicians, it also appeared that the diet was not universally continued after the I-131 procedure. It should be noted, however, that as I-131 has a half life of 8 days, it might be appropriate to remain on the diet for at least 2 days after the I-131 treatment as suggested by OncoLink at the University of Pennsylvania Cancer Centre. (2, 23) Based on the diet information provided by each facility included in this study, it seemed that only Kingston General Hospital in Ontario and Queen Elizabeth II Health Sciences Centre in Nova Scotia are currently adopting this practice to help increase I-131 uptake by the body. Therefore, it is believed that the duration of LID should be dependent on the nature of the procedure. Clinical trials by each facility might be necessary to determine the actual duration of the diet required prior to and after each procedure. This is because each facility might have different practices in terms of their I-131 procedures (e.g. dosage) that might affect the required duration of the diet. By doing so, it could help prevent putting a patient on the diet unnecessarily for the duration it was prescribed. For instance, a patient might no longer need to remain on the diet after all I-131 scans were completed, whereas another patient might need to stay on the diet for a short period of time after the I-131 treatment. The information on the duration of the diet required for each procedure should be clearly stated on the patient diet information handout. It should also be clarified by the physician at the time when the procedure is completed. Not surprisingly, the route of delivering recommendations, the actual instructions given by physicians and dietitians, their personal beliefs on the diet, as well as the
  54. 54. content of their patient diet handouts were very different from each other. As these have already been described in detail under the RESULTS section, they would not be repeated in here again. However, one thing that needed to be pointed out was that even though some physicians did recommend the diet, they might not necessarily be providing the same written and/or verbal instructions to all their patients. It depended on a variety of reasons, including whether they had other non-diet information that they needed to go through with their patients first, or whether they actually remembered giving their patients some verbal diet instructions as those instructions were not officially written down. Recommendations that could be made to address this inconsistency included: physicians should routinely provide some verbal (and written, if possible) diet instructions at the same time when they are going through the precautionary guidelines with their patients. If time is really limited, the list of avoided foods should at least be reviewed with their patients. This could help to ensure that the patients would understand that certain foods are important to avoid, so that the outcome of their scans and treatments could become more effective. It appeared that most physicians and dietitians did not generally have any specific level of iodine intake restriction. It was believed that it would be more important to find a balance between the benefits of the diet and the compliance of the patients. Physicians generally told their patients verbally to avoid certain food items, while dietitians usually had a list of avoided foods (and allowed foods in some cases) for their patients to follow. For those who were able to state the recommended iodine intake restriction of their LIDs, 50 ug iodine daily was the most common restriction level and it
  55. 55. was also similar to the restriction level recommended by various literature studies. Currently, the Daily Recommended Intake (DRI) of iodine is 150 ug / day. (17) Only 47% of dietitians who returned the questionnaire have had experiences counseling patients on LID because physicians’ referral to a dietitian for LID counseling was uncommon. Although referral to a dietitian is admittedly not necessary for all patients due to priority issue, it might still be beneficial if physicians (nurses and/or nuclear medicine technicians who also provide patient education on LID in some facilities) could determine each patient’s need for diet counseling. For instance, it might be appropriate to refer a patient to a dietitian if the patient has a poor appetite, or is very confused with the diet instructions. The bottom line is a diet handout would be essential and some form of access to a dietitian by patients would also be beneficial. This could easily be done by printing the contact information (e.g. name and phone number) of a dietitian on the patient diet information handout. If patients have questions regarding the diet, they could call the dietitian for questions. This practice has been used successfully by a few facilities. It was interesting that of all the dietitians who have seen patients for LID counseling, all of them have received feedback from patients. This was different from the physicians’ responses in which only 2 out of 6 of them have received feedback from their patients. This again showed that it would be beneficial for physicians to refer some of their patients to a dietitian because some patients do have questions and concerns regarding the diet, and require assess to professional diet counseling by dietitians. This would especially be true if patients have concurrent health problems such as diabetes. As well, it might be worthwhile for some facilities to revise their diet handouts, such that
  56. 56. more up-to-date, patient-friendly information could be provided without confusing and causing anxiety in their patients. The diet itself might need to be made less stringent in some facilities as well. Based on the feedbacks gathered from physicians and dietitians, it appeared that effective education material would be very essential. As mentioned, routine referral to a dietitian for LID counseling might not be necessary for all patients. However, physicians (or anyone who are responsible for patient education in the Nuclear Medicine Department) should still routinely provide adequate LID information to their patients. The information provided by them should also be consistent with that of dietitians. This is necessary to avoid confusion, and to prevent reducing the potential benefits of LID. The following recommendations would be useful when developing a new patient diet handout. Generally, it would be beneficial if the patient diet handout could provide the following information: 1. The duration of low-iodine diet before and/or after the I-131 procedure(s) 2. A list of allowed and avoided foods; be specific and give examples (e.g. specific brand name of cheese or specific type of juice patients can consume) 3. The number of servings and serving sizes allowed for each food category 4. Information on where to get those special products (e.g. salt-free, iodine-free bread) 5. Sample meal plans with breakfasts, lunches, suppers, and snacks 6. A collection of low-iodine diet recipes (available at www.thyca.org) 7. Dietitian’s contact information
  57. 57. It is said that the average Canadian’s daily intake of iodine is 1000 ug. (20) However, it was difficult to estimate the iodine content of each LID because the Canadian Nutrient File does not include the iodine content of foods. Depending on the geographical location, variable amounts of iodine can be found in human foods. (17-19) In general, the iodine content of foods reflects the concentrations of iodine and fertilizer of the soil in which plants are cultivated, or on which animals graze. (18, 19) The amount of iodine in drinking water also depends on the iodine content of the rocks and soils of a geographical area. (19) As the ocean provides plentiful amounts of iodine, all foods coming from it (e.g. seafood and salt water fish) are the richest sources of iodine. (17, 18) Significant amounts of iodine can also enter the food chain through disinfectants in dairy processing, coloring agents, and dough conditioners. (17) All table salt in Canada is also iodized to prevent goiter. (17, 18) However, sea salt (unless it is iodized) provides little iodine because iodine will become a gas during the salt-drying process. (18) It is beyond the scope of this research study to come up with a set of standardized recommendations for LID. However, a new LID handout is currently under the process of development by a group of physicians and dietitians at the Vancouver Cancer Centre and Vancouver General Hospital. In the meantime, Tables 3-5 contained diet recommendations from various hospitals in British Columbia, Nova Scotia and Ontario and can be used as references. Before a new diet handout is completed, the following considerations might be worth the attention of physicians, dietitians, or anyone who is responsible for developing a patient LID handout:
  58. 58. 1. As suggested by Pluijmen et al, it is sufficient to start a LID 4 days prior to the I-131 procedure. (22) During a recent discussion with Dr. Powe and Dr. Worsley at the Vancouver General Hospital Nuclear Medicine Department, they have also decided to change the duration of their LID from 14 days to 7 days. (24) This is because they believed that the longer the duration of the diet, the lower the compliance of the patient will be. (24) They also suggested that a normal diet can be resumed 3 days after the I-131 treatment, OR as soon as the patient can resume his/her thyroid hormone as directed by his/her physician. (24) This is because they believed that it will not make sense if the patient has to stay on the diet while he/she has already re-started his/her thyroid hormone therapy. (24) 2. Ensure foods from different food groups are included in the LID. This is because while a LID might not be nutritionally adequate, an effort to make it as nutritionally adequate and palatable as possible should be made. A small amount of “avoided foods” might be allowed to increase variety and palatability. For instance, instead of completely avoiding milk and eggs, ½ cup of milk per day and less than 3 eggs per week might be allowed. 3. It might be worthwhile to trial the diet approach adopted by Kingston General Hospital in Ontario, in which high iodine foods would be avoided for a longer period of time (e.g. 6 weeks), while the actual LID does not need to be initiated until one week prior to the procedure. 4. An informal market research on the content of nutritional supplements was done by the author of this study a year ago. It was found that certain
  59. 59. multivitamin/mineral supplements contain only a very small amount of iodine, and its benefits to some patients whose food intake is poor might outweigh its drawback. For instance, compared with the 4.2 ug iodine provided by a 3 oz beef portion (21), Centrum Forte only provides 0.15 ug per capsule. Examples of multivitamin/mineral supplements that provide < 0.20 ug iodine/capsule included: a. Centrum Multivitamin-Multimineral Formula – 0.15 ug b. Nu-Life the Ultimate One for Men (Active) – 0.20 ug c. Nu-Life the Ultimate One for Men 50 Plus – 0.10 ug d. Nu-Life the Ultimate One for Women 50 Plus – 0.20 ug e. Jamieson Natural Source Basic Vita-Vim Level 1 Potency Multivitamin – 0.15 ug f. Jamieson Natural Source Mega-Vim Level 4 Potency Multivitamin – 0.10 ug g. Nature Made – 0.15 ug h. Quest Super Once A Day Multiple Vitamins & Chelated Minerals (Time Released) – 0.10 ug i. Alive Brand Vitamins Complete One-A-Day Vitamins & Minerals – 0.10 ug It should be noted that the use of multivitamin/mineral supplements in a LID is not advocated in this study. However, the above information might help physicians and dietitians answer their patients’ enquiries regarding the use of their routine multivitamin/mineral supplements. The bottom line is: not all
  60. 60. multivitamin/mineral supplements contain a large dose of iodine. Continuation or avoidance of the use of multivitamin/mineral supplements should be determined by physicians or dietitians on an individual basis. 5. A daily calcium supplementation with 1200 mg calcium carbonate is recommended as LIDs are generally low in calcium. 6. Vancouver city water has a low iodine content as per UBC Food Information Services (25) and City of Vancouver Engineering Department - Water Design (26). Therefore, distilled water might no longer be essential if patients are residing in the Greater Vancouver Regional District. However, the use of distilled water might still be needed in other geographical areas unless the iodine content of their local water is also clarified. Generally, 12 cups of water (or distilled water) should be consumed daily to help get rid of the I-131 in the body. Distilled water should be used in the preparation of foods if the iodine content of local water has not been clarified yet. 7. Restaurant, manufactured, and processed foods (including canned, dried, salted, or cured meat) should be avoided due to the unknown amount of iodized salt used. Fresh and homemade foods are preferred. 8. Certain foods are important to avoid or restrict because they are the richest source of iodine. For instance: a. Seafoods (e.g. clams, lobsters, oysters, sardines), and other salt water fish (3, 5, 8,16,17,18, 22) b. Food products containing seaweed or seaweed by-products such as carrageen, agar-agar, algin, alginate, and nori (3, 8,16-18, 22)
  61. 61. c. Commercial breads and grain products made from bread dough. (3, 5, 8, 16, 22), This is because the dough oxidizers or conditioners contain 500 mg iodates per 100 g bread. (19) d. Dairy products including chocolate (3, 5, 8, 16, 17) e. Eggs, egg yolks, or foods containing eggs. (5, 8, 16, 22) Egg whites do not contain iodine and therefore, are acceptable. (16) f. Table salt or any foods containing iodized salt (e.g. fast foods). (5, 8, 16, 22) Iodized salt provides 76 ug iodine per gram of salt. (17) Non- iodized salt will be the alternate for table salt. (16) Patients should be reminded that sodium chloride itself does not contain iodine. In other words, as long as the salt is not iodized, it can still be included in the diet. (16) g. Red, orange, or brown processed foods and medications (5, 8,16, 22) h. Molasses (sulfured) (16) i. Soy products (e.g. soy milk, tofu). Soy sauce contains ~0.1 ug per tablespoon. (21) However, iodine content in soy products can vary and some are moderately high in iodine. (16) j. Red kidney beans, lima beans, navy beans, pinto beans, cowpeas (3, 5, 16) k. Potato skins contain iodine. Potato flesh is fine. (3, 16) l. Rhubarb (16) 9. Certain foods such as butter and margarine could be liberalized. Both of them contain minimal iodine (0.3 – 0.4 ug iodine / tbsp). (21) The iodine contents of
  62. 62. meat, vegetables, fruits, grains and cereals are also generally lower than foods such as iodized salt and seafood. Therefore, it might be worthwhile for some facilities to liberalize the restriction level of their LIDs. A few food items under the avoided list from above might also be allowed in small quantities. Examples include milk, egg, and cheese. However, it is still recommended for patients to choose products with lower iodine contents within the same food category (e.g. cream cheese – 0.9 ug iodine/oz vs. cheddar cheese - 2.6 ug iodine/oz). By liberalizing the diet, the palatability and the nutrient content of the diet can be improved. This is very important for cancer patients whose appetite might already be poor while nutritional needs are still high. 10. To avoid confusion, patients should generally be recommended to avoid all fish and seafood. However, a small quantity of fresh water fish might be allowed in the diet under special circumstances (e.g. the patient is a pesco- vegetarian who excludes red meat and poultry in his/her diet). There is only 20 to 40 ug iodine / kg compared with 300 to 3000 ug iodine / kg from salt water fish (17, 19). 11. While it might be beneficial to liberalize the diet, it is also important to specify the number of servings allowed for each food category. For instance, a 3 oz turkey portion only provides 4.2 ug iodine. (21) However, if 12 oz of turkey is consumed in a day, it will provide as much as 16.4 ug iodine. 12. The diet should be personalized to adapt to each individual’s needs (e.g. diabetes)
  63. 63. Appendix 3 shows the iodine content of foods. It is an excerpt from a book called Nuclear Medicine Therapy by Harbert J.C. (21) It is recommended by the Thyroid Cancer Survivors’ Association, Inc. that patients should avoid foods high in iodine (> 20 ug / serving) and limit foods moderate in iodine (5 to 20 ug / serving) during their time on the LID. (16) Foods that are low in iodine (< 5 ug / serving) could be consumed freely. (16) It should be noted, however, that there are huge discrepancies in terms of the iodine content of foods. Different studies/sources have different figures. As stated, the iodine content of foods in this study was mostly based on Nuclear Medicine Therapy by John C Harbert. (21) However, the true iodine content of a Canadian LID could not be accurately determined unless data on iodine content of Canadian foods become available. Due to the limited availability of physicians and dietitians who had the knowledge on LID, pilot testing was not done prior to the actual distribution of questionnaires. However, general comments from a physician and several dietitians were gathered and the questionnaires were revised several times before the questions were finalized. Despite the special effort made to ensure that all relevant questions were included in the questionnaires, there were still a few questions that should have been included. For the physicians’ questionnaire, it would be interesting to find out whether they would normally review the written instructions with their patients. By asking such a question, it could reveal how much emphasis the physicians would put on the diet. This is important because it could influence their patients’ understanding, as well as their compliance to the diet. As for the dietitians’ questionnaire, it would be interesting to find out whether the patients were self-referred or were referred by their physicians to a dietitian. As well,

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