This document summarizes and compares guidelines from seven professional organizations - ATA, ESMO, BTA, NCCN, SNM, EANM, CSE - regarding the prescribed radioactive iodine (131I) activity for remnant ablation in patients with differentiated thyroid cancer. Most guidelines recommend 30-100 mCi. However, the objectives and definitions vary - ablation is defined as eliminating thyroid remnant by some, but may also treat microscopic tumors by others. Two recent randomized controlled trials found that 30 mCi was as effective as 100 mCi for ablation, with fewer side effects. Successful ablation can be achieved with as little as 30 mCi according to these studies and ATA guidelines.

1. Guidelines for the prescribed activity for 131I remnant ablation on differentiated thyroid cancer:
a distillation and comparison of guidelines from seven organizations.
Guan H1, Van Nostrand D2, Li Y3, Orquiza M2, Teng W1, Khorjekar G2
1Dept Endocrinology & Metabolism and Inst of Endocrinology. The First Hosp of China Med Univ, Shenyang, Liaoning Province 110001, P.R.China
2Div of Nuclear Medicine, Dept Medicine, MedStar Washington Hosp Ctr, Washington, D.C.
3Dept Nuclear Medicine, The First Hosp of China Med Univ, Shenyang, Liaoning Province 110001, P.R.China
Abstract
Objectives:
The objective of this educational exhibit is to compare the
prescribed activity for 131I remnant ablation in patients with
differentiated thyroid cancer (DTC) as proposed by the following
professional organizations:
- American Thyroid Association (ATA)
- European Society for Medical Oncology (ESMO)
- British Thyroid Association (BTA)
- National Comprehensive Cancer Network (NCCN)
- Society of Nuclear Medicine (SNM)
- European Association of Nuclear Medicine (EANM)
- Chinese Society of Endocrinology (CSE) / Chinese Society of
Surgery (CSS) / Chinese Anti-Cancer Association (CACA) /
Chinese Society of Nuclear Medicine (CSNM)
Summary:
131I is an important treatment modality for patients with
differentiated thyroid cancer, and 131I has been documented as
having utility for remnant ablation. However, the prescribed
activity for 131I remnant ablation is controversial, and multiple
professional organizations worldwide have published guidelines
addressing the prescribed activity of 131I remnant ablation.
This educational exhibit distills and compares the various
professional organizations’ guidelines for the prescribed activity
of 131I for remnant ablation in patients with differentiated
thyroid cancer. This educational exhibit also reviews the recent
reports of Mallick et al. and Schlumberger et al., both of which
evaluated the efficacy of 1.1 GBq (30 mCi) and 3.7 GBq (100 mCi)
of 131I for remnant ablation.
Definitions of Ablation
Guidelines Discussion
Guidelines Recommendation
ATA 2009
RECOMMENDATION 36: “The minimum activity (30–100 mCi) (i.e. 1.1 – 3.7GBq) necessary to achieve successful remnant ablation should be
utilized, particularly for low-risk patients.” Recommendation rating: B
BTA 2007
“The present recommendation for remnant ablation is 3.7 GBq (i.e. 100 mCi) pending the results of ongoing trials (III, B).”
Comment: The BTA does not distinguish “remnant ablation,” “adjuvant treatment,” and treatment of loco-regional disease from each other for the
first 131I therapy.
CSE/CSS/CACA/
CSNM 2012
RECOMMENDATION 2-14: For low- and intermediate-risk patients, the recommended activity of radioiodine for remnant ablation is 1.1 - 3.7 GBq
(30 - 100 mCi). Recommendation rating: B
RECOMMENDATION 2-15: For intermediate to high risk patients, the recommended activity of radioiodine for remnant ablation is 3.7 – 7.4 GBq
(100 - 200 mCi). This activity also serves to treat microscopic tumor deposits (adjuvant treatment) and metastatic disease (treatment).
Recommendation rating: C
EANM 2008 “ The ‘optimal’ activity for radioiodine ablation of post-surgical thyroid residues macroscopic disease is generally a single administration of
1–5 GBq (i.e. 27 – 135 mCi), but within that range, remains controversial, with different centers advocating use of 1.11, 1.85 or 3.7 GBq.”
ESMO 2012
“In addition, in the recent years, it has become increasingly apparent that successful thyroid ablation may be achieved using low activities of 131I
(1110–1850 MBq) (i.e. 30 - 50 mCi). ”
NCCN 2011
If “. . . suspected or proven thyroid bed uptake,” then “. . . consider adjuvant radioiodine ablation (30 mCi to 100 mCi) (i.e. 1.1 – 3.7 GBq) to
destroy residual thyroid function . . . .”
Comment: The guideline emphasizes that the indications for ablation be based on suspected or proven RAI uptake in the thyroid bed.
SNM 2012 “For postoperative ablation of thyroid bed remnants, activity in the range of 1.11–3.7 GBq (30– 100 mCi) is typically prescribed, depending on the
radioiodine uptake measurement and amount of residual functioning tissue present.”
Conclusion
References
1. Cooper D, Doherty G, Haugen B, et al. Revised American Thyroid
Association management guidelines for patients with thyroid nodules
and differentiated thyroid cancer. Thyroid 2009,19:1167-1214.
2. Pacini F, Castagna MG, Brilli L, et al. Thyroid cancer: ESMO Clinical
Practice Guidelines for diagnosis, treatment and follow-up. Annals of
Oncology 2010;21(S5):v214–v219.
3. British Thyroid Association and Royal College of Physicians.
Guidelines for the management of thyroid cancer. Second Edition.
2007.
4. National Comprehensive Cancer Network (NCCN). Clinical Practice
Guidelines in Oncology. Thyroid Carcinoma. V.3.2011
5. Silberstein E, Alavi A, Balon H, et al. The SNMMI Practice Guideline for
Therapy of Thyroid Disease with 131I 3.0. J Nucl Med 2012;53:1633-
1651.
6. Luster M, Clarke E, Dietlein M, et al. Guidelines for radioiodine
therapy of differentiated thyroid cancer. Eur J Nucl Med Mol Imaging
2008;35:1941-1959.
7. The Chinese guideline for management of thyroid nodules and
differentiated thyroid cancer. Chin J Endocrinol Metab 2012, 28:779-
797.
8. Mallick U, Harmer C, Yap B, et al. Ablation with low-dose radioiodine
and thyrotropin alfa in thyroid cancer. N Engl J Med 2012;366:1674-
1685.
9. Schlumberger M, Catargi B, Borget I, et al. Strategies of radioiodine
ablation in patients with low-risk thyroid cancer. N Engl J Med
2012;366:1663-1673.
Although all organizations, except ESMO, clearly define
‘ablation’ as the use of 131I to eliminate the postsurgical thyroid
remnant (ATA, BTA, SNM, EANM, CSE) or destroy residual thyroid
function (NCCN), this dose of 131I may also serve to treat
microscopic tumor deposits (adjuvant treatment) and metastatic
disease (treatment) according to their indications for
postoperative RAI ablation in some guidelines (ATA, BTA, NCCN,
EANM, CSE).
As a matter of terminology, the amount of radioiodine
given in the ablation procedure remains controversial. The
objective of first 131I therapy may affect prescribed activity of
131I administered.
Most guidelines recommend the range of prescribed
activities for remnant ablation to be 30-100mCi. ESMO prefers
using low activities. BTA’s guideline actually recommends 131I
activities for “first therapy”, which includes ‘ablation’, and
potential ‘adjuvant treatment’ and ‘treatment’. China’s
guideline recommends different activities based on risk
stratifications and objectives of first 131I therapy. Two recent
prospective, large, multi-institutional studies have confirmed
that 30 mCi of 131I may achieve successful remnant ablation.
Recent Evidence: Effectiveness of 30 mCi vs. 100 mCi
From the United Kingdom: Mallick U, et al. N Engl J Med. 2012;366:1674-1685. From France: Schlumberger M, et al. N Engl J Med. 2012;366:1663-1673.
• Prospective, randomized non-inferiority study.
• United Kingdom, 29 centers, 421 patients.
• Patients consist of T1 to T3 with the possibility of lymph node
involvement but no distant metastases and no microscopic residual
disease (e.g. N0, NX, N1, and MO).
• Patients excluded with aggressive histology.
• Definition of ablation was negative scan (<0.1% uptake) and Tg < 2.0
ng/ml 6 to 9 months.
• CONCLUSION: Low dose (30 mCi) was as effective (85%) as high-dose
(100 mCi) (89%) of 131I with a lower rate of adverse events.
• Discussion: Future recurrence were not addressed.
• Prospective, randomized study.
• France, 24 centers, 684 patients.
• Patients consist of pT1a (< 1cm) and N1 or Nx or pT1b >1 to 2 cm)
and any N or pT2 (2 < 4 cm) N0, absence of distant metastasis.
• Ablation was considered complete when neck ultrasonography
was “normal” and rhTSH stimulated serum thyroglobulin was < l
ng/ml or a diagnostic 131I total body scan was “normal” when Tg
antibodies were present at (8±2) months follow-up.
• CONCLUSION: 30 mCi was as effective as high-dose (100 mCi) of
131I with a lower rate of adverse events.
• Discussion: 30 mCi may also be as effective as 100 mCi in reducing
future recurrence, but further study is warranted.
Remnant ablation as defined by the ATA may be
successfully achieved with as little as 1.11 GBq (30 mCi) of 131I.