Colorectal cancer screening and computerized tomographic colonography


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Colorectal cancer screening and computerized tomographic colonography

  1. 1. 115B.D. Cash (ed.), Colorectal Cancer Screening and Computerized Tomographic Colonography: A ComprehensiveOverview, DOI 10.1007/978-1-4614-5943-9_6, © Springer Science+Business Media New York 2013IntroductionScreening for colorectal neoplasms has become thestandard of care in advanced medical settingsworldwide [1–7]. Identifying asymptomatic col-orectal neoplastic lesions has been shown to reducecolorectal cancer (CRC) incidence and the overallcost of medical care. Clinicians have several alter-natives at their disposal as they consider screeningfor their respective patient population. Many orga-nizations have devoted considerable time weighingthe evidence to establish appropriate evidence-based guidelines directing clinicians with methodsto appropriately manage screening. CT colonos-copy and optical colonoscopy (OC) are viablealternatives for CRC screening. Organizations thatplan to utilize both modalities must consider mul-tiple issues to effectively integrate and ensure ahigh-quality screening program.Optical ColonoscopyClinicians use OC as a primary means to screenthe entire colon not only for cancer but alsofor precancerous adenomatous lesions. Mostadenomas may be removed at the time of OC.The size, location, shape, and pathologic natureof polyps may be determined during this singleclinical encounter, providing the patient and cli-nician with valuable information to guide thefuture CRC screening strategy. Often, the clini-cian doing the endoscopic procedure has anestablished relationship with the patient and mayprovide recommendations regarding care at asubsequent clinical encounter. EstablishedCenters of Digestive Health, worldwide, haveproved to be successful in driving the CRCscreening effort. Brenner et al. demonstrated avery low incidence of CRC after a negativescreening OC in low-risk groups and suggested a10-year screening interval after a negative OC [8].Screening OC is a highly effective tool for CRCprevention.Clearly, many patients and healthcare provid-ers are comfortable with this protocol of patientcare. However, OC has its disadvantages. Theprocedure requires adequate colon cleansing toallow for complete mucosal evaluation, and manypatients state that the arduous task of colonicpreparation is a major drawback to the entire pro-cess. In almost every case, OC requires conscioussedation of one form or another. Individual clini-cal evaluation of the patient’s overall medicalcondition is required to determine candidacy forsedation. From the patient’s perspective, con-scious sedation provides them comfort and allaysanxiety; it also requires access to reliable trans-portation from the medical setting. As a result,patients not only have to absent themselves fromS. Carpenter, M.D.(*)Mercer University School of Medicine,Savannah Campus, Savannah, GA, USADepartment of Internal Medicine, Memorial UniversityMedical Center, Savannah, GA, USAe-mail: slcarp2@gmail.com6Integration of CTC into a CRCScreening ProgramSteven Carpenter
  2. 2. 116 S. Carpentertheir daily responsibilities but their transportermust also take time from their routines. This is asignificant issue to consider when reviewing theoverall cost of the CRC screening effort. DuringOC and polypectomy, perforation of the colonmay occur. Although this is a relatively rare com-plication, it can and does occur in the care ofasymptomatic patients. In addition, bleeding evenafter the most simple of polypectomies may occurand may require hospitalization or even adminis-tration of blood products. Because of the poten-tial for colonic perforation, post-polypectomybleeding, and other complications, adequatelytrained medical personnel must carefully discussthese possibilities to obtain meaningful informedconsent from all patients prior to the procedure.There is simply no substitute for an excellentpatient–physician relationship.QualityFirst and foremost in managing a CRC screeningprogram should be quality and safety [9]. Opticalcolonoscopy is not a perfect screening modality.There are a variety of issues that have come to theforefront in this regard. Among these are ade-noma detection rates (ADR), colonoscopic with-drawal times, and preparation quality [10]. Thereis good evidence that quality of OC varies andthat this variation has an impact on effectiveness[11–13]. Several tandem OC studies demonstratethat, for many reasons, adenomatous colon pol-yps may be missed during the procedure [14, 15].Polyps may be behind folds, obscured by colonicdebris, or simply not seen by the endoscopist.This issue has prompted considerable focus bygastrointestinal societies on measurement andreporting of quality parameters. Many endoscopycenters have initiated routine documentation ofthese important quality measures, and collec-tively, there is hope that these developments canimprove the overall CRC screening effort. Severalstudies demonstrate that adequate training andexperience translate into improved quality. Werequire additional experienced endoscopists tomeet future screening needs, and quality measuresare now included in gastroenterology fellowshipcurricula. As the age of our patient populationincreases and the population grows, endoscopistsand trainees need a firm grasp of advances inendoscopy (with its inherent limitations) and afostered appreciation of their role in qualityimprovement during CRC screening.Adenoma Detection RatesUltimately, the entire purpose of CRC screeningis to prevent CRC, and this is facilitated byidentification of colonic adenomas, its precursorlesion. Ideally, these polyps will be identified atan early stage when resection is relativelystraightforward. The ADR has become a keymeasure for the relative effectiveness of OCscreening [16]. Among healthy asymptomaticpatients undergoing screening OC, estimates sug-gest adenomas should be detected in 25% or moreof men and 15% or more of women 50 years ofage and older. A variety of factors may influenceADR. Patient-associated variables that mightaffect the efficacy of OC include body massindex, medications, and comorbid illness. Variousreports have documented the potential for effectof OC withdrawal time, completeness of OC(cecal intubation), adequate bowel preparation,participation of trainees in the procedure, experi-ence, and procedural timing during the workday.Physician fatigue has received increased atten-tion in all fields of medicine. It is not surprisingthat attention has been directed toward this vari-able. There are data that suggest the ADR may benegatively affected if the procedure is completedat the end of the endoscopist’s day as opposed tothe beginning. Approaching this issue may provedifficult for screening centers as they attempt tomeet demand. Optimal utilization of physicianand endoscopy center resources is required.Some centers have approached this issue by split-ting the endoscopy workday. There is some rea-son to believe that endoscopists function moreeffectively when working in 4–5 h blocks asopposed to 8–10 blocks. Gurudu et al. [17] docu-mented that the afternoon ADR was significantlylower than the morning ADR (21.0% vs. 26.1%;OR=0.75; P=0.02). When endoscopists werescheduled to work in half-day blocks, morningand afternoon ADR was not statistically different
  3. 3. 1176 Integration of CTC into a CRC Screening Program(27.6% vs. 26.6%;OR=1.05; P=0.56). Lee et al.identified a 12.4% reduction in detected polypswhen comparing morning procedures with after-noon procedures performed by the same endos-copist [18]. In fact, as each hour in the dayelapsed, they reported a 4.6% reduction in polypdetection (P=0.005).These assertions make intuitive sense andhave been documented in other manuscripts [19,20]. Perhaps, prolonged procedure blocks createvisual or mental fatigue that may adversely affectadenoma detection. Others have proposed thatcolonic preparation is inferior later in the day,and mucosal visualization, not fatigue, is the keyvariable. It is also possible that endoscopists’ADR declines if they fall behind on their sched-ule as the day progresses. It is imperative thatendoscopists recognize the potential that fatigueand procedural timing may affect their personalADR. Centers for digestive health must acknowl-edge this fact and take these data into account aspatient care scheduling templates are devised.The issue of ADR and endoscopist fatigue is acrucial consideration if one plans to integrateCTC into an existing CRC screening program[21]. The goal of CTC is to identify polyp candi-dates and deal with them. Patients are reluctant totake a colonic preparation to begin with and oftenare not interested in coming back another day foran OC requiring a second round of colonic prepa-ration. Therefore, scheduling matrices must beestablished to allow for same-day OC in thosepatients who have identified polyp candidates byCTC. Anecdotal reports suggest that wait timesfor same-day OC after positive CTC may be 2 hor even longer. Many of these same-day OCs willhave to be performed in the afternoon. It is unde-termined whether this strategy for CRC screen-ing is flawed due to the issue of endoscopistfatigue. Further study in this area will be requiredif CTC ever becomes a dominant CRC screeningstrategy.Bowel PreparationBoth CTC and OC require bowel preparation toenhance visualization of colonic mucosal detail[22]. Bowel preparation may be the most despisedaspect of CRC screening from the patient’sperspective. Poor patient acceptance is commonto both OC and CTC, and the quality of bowelpreparation directly impacts the quality of bothstudies. In a large retrospective case study byLebwohl et al., the adenoma miss rate for OCperformed with suboptimal bowel preparationwas high [23]. These authors concluded that poorbowel preparation decreases OC effectivenessand should mandate an earlier follow-up exami-nation. Also, suboptimal bowel preparationmakes OC more difficult and increases proce-dural time. Both the intubation and withdrawalphases are prolonged. In addition, the cecal intu-bation and polyp detection rates are decreased[24, 25]. Froehlich et al., in a large prospectivetrial, observed that small and large polyp detec-tion rates were increased in patients with an ade-quate bowel preparation compared to thoseinadequately prepped (29% vs. 26%, P<0.001).In this study, the cecal intubation time wassignificantly decreased in patients with adequatepreparations (11.9 min vs. 16.1 min, P<0.001).Careful attention to patient education regardingthe preparation process will increase CRC screeningcenter efficiency and the quality of patient care.Polyethylene glycol electrolyte lavage solu-tion (PEG) is widely utilized as a bowel prepara-tive in OC (NuLYTELY, GoLYTELY, BraintreeLaboratories). Patients have reported difficultywith the 4 L volume of this traditional prepara-tion, and subsequently, 2-L preparations(HalfLytely, Braintree Laboratories) were devisedusing either magnesium citrate or bisacodyl tab-lets [26]. Later, an alternate 2-L preparation con-taining PEG, ascorbic acid, and sodium sulfate(MoviPrep, Salix Pharmaceuticals, Inc.,Morrisville, NC) was devised. This preparationhas been shown to be non-inferior to the tradi-tional 4-L PEG preparation [27]. Previously, anoral sodium phosphate preparation (Fleet’sPhospho-soda, C.B. Fleet Company, Inc.,Lynchburg, VA) was widely utilized for bowelpreparation. In 2008, the FDA issued a safetyalert due to reports of acute phosphate nephropa-thy. In response, C.B. Fleet withdrew their oralsodium phosphate products intended for use asan OC preparative regimen [28, 29]. Morerecently, a bowel purgative regimen containing
  4. 4. 118 S. Carpentersodium sulfate 35 g, potassium sulfate 6.26 g, andmagnesium sulfate 3.2 g in divided doses (totalvolume, 2.8 L) was devised (SuPrep, BraintreeLaboratories). This split-dosed preparation favor-ably impacted patient acceptance [30].Split dosing of bowel preparations has becomevery popular in endoscopy centers primarily dueto the considerable improvement in mucosalvisualization and ease of the OC associated withthis administration schedule [31]. Split dosing ofthe bowel preparation has been recommended bythe American College of Gastroenterology toimprove effectiveness of bowel cleansing.Administration of one-half of the bowel prepara-tion during the evening prior to the procedure fol-lowed by ingestion of the second half of the prepduring the morning of the procedure producesconsiderable improvement in mucosal visualiza-tion.An interval of 6 h or less between the seconddose of the preparation and OC has been shownin several studies to be superior. The duration ofthe interval between the completion of bowelpreparation and the start of OC has been shown toimpact bowel-preparation quality [32]. Bowel-preparation quality is inversely related to the timeof the last preparation dose. Prior to this study,Church had concluded that small bowel contentsentering the right colon after preparation comple-tion had a deleterious effect on preparation qual-ity, primarily in the right colon [33]. Some haveproposed that this might explain the difficulty indemonstrating that OC is effective in the preven-tion of right-sided CRC [34]. There are a numberof excellent studies that note the superiority ofsplit-dosed colonic preparation relative to 1-daydosing regimens. Aoun et al. found that the split-dosed regimen was more likely to result in anexcellent preparation rating than if the entirepreparation was administered the evening beforethe OC (44.1% vs. 5.5%; P<0.001) [35].Emerging data suggests that the improvement inbowel preparation quality with split-dosed prepsresults in improved detection of neoplasia [36].Patient acceptance of the split-dosed schema isvariable. If the patient is scheduled for an 8 AMprocedure, it is necessary that they ingest thesecond dose of the bowel purgative between 12AM and 2 AM on the day of the procedure.Nonetheless, there is some evidence that patientsdo prefer the divided preparation compared to theprior standard 4-L preparation, despite the poten-tial timing inconveniences [37].Considerable advances have been made inunderstanding of quality bowel preparation. CRCscreening centers should maintain focus on devel-opments in this arena. Particularly, it is importantthat patient education prior to the procedureremains a priority. Patient acceptance of thebowel preparation process will continue to be abarrier affecting adherence to CRC screening.Withdrawal TimeThere is considerable evidence that quality OC isdirectly related to the duration of the procedure[38, 39]. Polyp detection rate is directly related tomean procedural time. Many endoscopists con-centrate on good technique and safety duringcolonoscope insertion and reserve the withdrawalperiod for careful mucosal visualization. Thecolonoscopic withdrawal time has received con-siderable attention in the literature. Indeed, it hasbeen proven to be a useful and easily acquiredquality measure. Barclay et al. noted that colonos-copists with mean withdrawal time of 6 min ormore had higher rates of detection of any neopla-sia when compared to those with mean with-drawal time of less than 6 min (28.3% vs. 11.8%,P<0.001) [12]. This also proved true for thedetection of advanced neoplasia (6.4% vs. 2.6%,P=0.005).These results have been confirmed insubsequent studies. It is apparent that endosco-pists do respond to monitoring and feedback. Linet al. retrospectively reviewed 850 screening OCperformed by 10 endoscopists [40]. Withdrawaltimes, polyp detection rates, and patient satisfac-tion scores were determined and then shared,confidentially, with the endoscopists. Thereafter,541 screening OCs were prospectively evaluatedmeasuring the same parameters. After monitor-ing was initiated, mean withdrawal timeincreased from 6.57 to 8.07 min (P<0.0001),and polyp detection rates improved from 33.1 to38.1% (P<0.05). There was a small, statisticallyinsignificant increase in the neoplasia detection
  5. 5. 1196 Integration of CTC into a CRC Screening Programrate from 19.6 to 22.7% (P=0.17). There was nochange in mean patient satisfaction scores. The USMulti-Society Task Force on Colorectal Cancerrecommends 6–10 min as the minimal amount oftime needed for adequate inspection during thewithdrawal phase.Patient SatisfactionIt is important that all CRC screening centersmake patient satisfaction a top priority [41–43].There are many factors that influence overallpatient satisfaction. Clearly, patients are con-cerned about their physician’s technical skillsand sedation adequacy. The facility’s cleanlinessand focus on patient privacy are also importantmeasures impacting satisfaction. Gastrointestinaland recovery nurses play a major role in how ourpatients perceive the overall experience. CRCscreening centers should routinely measurepatient satisfaction in these, and potentially other,areas. Quality improvement initiatives need to bein place. Areas for potential improvement shouldbe defined and then appropriate changes in pro-cess may be implemented. The latter point is thekey. It does an institution little good to measurepatient feedback if one is not ready and willing toact upon the information. Actually, in practice,the process of quality improvement can be quiterewarding. Once you get the team focused onquality and improvement, the entire process willself-perpetuate.CT ColonographyCT colonography (CTC) is a promising CRCscreening tool. There are several key factors thatmake this method of CRC screening attractive toclinicians and patients. The procedure does notrequire moderate conscious sedation. Therefore,patients may provide their own transportation andreturn to work immediately following the exami-nation. Of course, this depends on whether theCTC has positive findings. If same-day OC is tobe considered in the event of a positive CTC, thenthe reading of the CTC must be immediate.Thereafter, the patient may decide for interventionon the CTC exam date. If a later date is selected,then a repeat colonic preparation will be required.As the colon is imaged digitally, the risk of proce-durally related complications, such as perforationand bleeding, is vastly reduced. Improvements inCTC technology image quality and data acquisi-tion time allow for a time-efficient examination.Patients may have their procedure completed in aslittle as 10 min with CTC. Importantly, CTC hasresulted in increased patient awareness of theCRC screening effort. As CTC has received con-siderable attention in the lay press, more patientsrealize the value of CRC screening and may bewilling to participate in the process. Anything thatincreases overall patient awareness and accep-tance of the process of CRC screening is beneficialand improves adherence.Despite these advantages, CTC has its ownlimitations. Many patients are disappointed todiscover that CTC requires adequate colon prepa-ration for optimal colonic imaging. In fact, thepreparation is more complicated as contrast- andfecal-tagging agents are necessary to adequatelydifferentiate stool from polyps. Trained medicalpersonnel are required to describe the importanceand specifics of this preparation to patients.Current screening recommendations suggest thatsome patients might have five or more CT exami-nations during their lifetime if CTC is the primaryCRC screening modality. Radiation exposureremains a major concern. The singular CTC examis not the issue. Cumulative radiation exposure,given CTC as the primary modality for CRCscreening, has drawn increased scrutiny by many.Radiology societies have largely dismissed thisissue [44]. The cumulative effects of medicalradiation in a screening effort are poorly under-stood and long-term studies are needed. If a polypis identified via CTC, most patients require OCfor polyp removal. Some have suggested thatsmall polyps may be followed with CTC at short-ened screening intervals. Although some patientsmay be comfortable with repeated CT examina-tions to follow a lesion, those in primary careknow other patients will have concern about thesafety of this watch-and-wait approach and theircumulative radiation exposure.
  6. 6. 120 S. CarpenterExtracolonic FindingsDuring CTC, extracolonic information is acquired[45]. A standardized CTC reporting and data sys-tem (C-RADS) has been developed and is usefulfor CTC report uniformity [46]. Findings ofmajor clinical relevance, categorized as E4findings, arise in approximately 4–10% of CTCexaminations. Examples of E4 findings includerenal cell carcinoma, ovarian carcinoma, and anabdominal aortic aneurysm of worrisome size.Indeterminate extracolonic abnormalities are cat-egorized as E3 findings in the C-RADS systemand are identified in approximately 30% of exam-inations. Examples of E3 findings include suspi-cious renal and liver cysts. Findings of lowclinical importance, such as simple liver andrenal cysts, are placed in category E2. The fre-quency of E3 findings may be expected toincrease, particularly if radiologists are liabilityaverse. Furthermore, in a liability-concernedenvironment, some radiologists may be inclinedto hedge on E2 abnormalities of low clinicalimportance, thereby increasing the percentage ofE3 findings reported [47]. The overall cost ofCRC screening would be expected to increasedue to repeat radiologic (and other) tests to fol-low indeterminate findings. In 2009, this impor-tant cost-efficacy concern impacted the decisionmade by the Centers for Medicare & MedicaidServices (CMS). Individual CT reports often sug-gest that E3 findings be followed at the discretionof the patient and referring physician. Just asADR and withdrawal times are important mea-sures of quality OC, the frequencies of E2 and E3findings are quality measures of CTC interpreta-tion. It is important that CRC screening centersutilizing CTC as an integral component put inplace a prospective measuring system to evaluatethereportingofextracolonicfindings.Radiologistsshould receive feedback about individual report-ing as compared to peers.Experienced clinicians know that patients worryabout extracolonic findings, no matter how minor.Health-related anxiety mandates time and patiencewhen discussing even simple E2 findings withpatients. In some cases, these discussions heightenthe individual patient’s health-care-related anxiety.An excellent doctor–patient relationship is usefulin lessening this degree of anxiety and provesinvaluable in many respects. For CTC to be clini-cally and cost effective, it is imperative that radi-ologists take great care in the nature of CTCextracolonic reporting and be prudent with E2 andE3 findings. CTC findings need to be communi-cated in a reliable manner by the radiologist to theclinician who is primarily responsible for thepatient. Likewise, primary care physicians or gas-troenterologists must communicate meaningfullywith patients. This seems straightforward, but in abusy clinical setting, failure to communicate isentirely possible.Interpretation of CTCAppropriately trained radiologists should inter-pret extracolonic findings identified at CTC.Although interpretation of extracolonic CTimages is thoroughly covered in gastroenterologytraining and many practicing gastroenterologistsreview multiple CT images within a given work-day, gastroenterologists do not have the expertiseor privileges to provide an official interpretationof extracolonic CT data. In CTC centers, oneprime goal is to provide the patient with theopportunity for a same-day OC. Within 20 or30 min, a gastroenterologist or radiologist read-ing CTC can provide an immediate intracolonicinterpretation as the patient waits. There is not asimilar acute need for the extracolonic interpreta-tion. CTC centers can send CT images digitallyand thus outsource the reading of extracolonicimages. Clinicians who provide CTC within theirown center therefore have the opportunity toidentify excellent radiologists who deliver high-quality interpretations. Small centers can evensend CTC images to major university centers.Several high-quality radiologists have developedtheir own corporations to provide this service,allowing CRC screening centers to track the qual-ity of extracolonic interpretations and change toan alternate vendor if necessary to ensure high-quality patient care. Extracolonic findings requirecareful evidence-based management. Colorectalcancer screening centered in one locale provides
  7. 7. 1216 Integration of CTC into a CRC Screening Programpatients with the opportunity to review anddiscuss colonic and extracolonic findings withtheir clinician during one clinical encounter.Appropriate evidence-based management of allfindings may be coordinated in this fashion.With regard to the interpretation of colonicfindings obtained during CTC, both radiologistsand gastroenterologists can perform this role, pro-vided that they commit the time to maintainingproficiency. Endoscopists have a wealth of experi-ence with OC, and reading three-dimensionalCTC flythrough images is thereby intuitive forthese practitioners. Standards for gastroenterolo-gists performing and interpreting diagnostic CTChave been established, and training programsorganized by professional gastrointestinal organi-zations are effective in orienting endoscopists tothis new technology [51]. Although courses canbe helpful for introduction, there is no substitutefor hands-on experience. This can be achieved viamentored leader programs. Ideally, personalhands-on experience is obtained in centers pro-viding CTC and OC services. Gastroenterologistsmay interpret colonic CTC images proficientlywith accuracy similar to that of radiologists [50].Adequate training and experience is mandatory toensure highly accurate readings. While colonos-copists may find CTC colonic interpretation intui-tive,thereisalearningcurvetoacquireproficiencywith the software utilized for CTC. There are sev-eral vendors with excellent CTC software pro-grams and platform revision is continuous.Gastroenterologists interested in CTC proficiencyshould select a single software and learn it well.The time commitment for CTC interpretive exper-tise is substantial, and maintenance of proficiencyis an ongoing process.CTC has become part of the gastrointestinalcore curriculum for GI fellowship training [48,49]. It is important that current gastroenterologyfellows develop a basic familiarity with the indica-tions, interpretation, and limitations of CTC.Coordination and cooperation with departments ofradiology can provide more in-depth training, andit is reasonable to consider formal radiology rota-tion addition to gastroenterology fellowship curri-cula. Novel educational tracts within traditionalgastroenterology training might be considered,with focus on technologies such as wireless capsuleendoscopy and CTC. A comprehensive trainingcurriculum would need to be established and train-ing standards for current fellows developed.Radiologists require a meaningful physicianpeer review program for accreditation. Thereexists no infrastructure in gastroenterology soci-eties for this type of quality control process.Randomly selected CTC studies need to be peerreviewedonaregularlyscheduledbasis.Althoughmembers of one’s own organization can feasiblyperform this task, this method of peer review maynot result in meaningful critique. Optimally,review networks would need to be organized,with reviewers able to correlate the interpretationwith corresponding endoscopic and pathologicfindings. Development of a national databasemight need to be considered. Thereby, CTC,endoscopic, and pathologic findings could becorrelated and meaningfully studied. Policies andprocedures must be in place to resolve discrepantpeer review findings providing the means forCTC centers to achieve quality outcomesimprovement [52]. Gastroenterology societieswould either partner with other societies todevelop appropriate peer review, quality, andsafety measures or initiate the process indepen-dently. Available data confirm that gastroenterol-ogists have the expertise to proficiently interpretCTC images, meaningfully participate in thisCRC screening approach, and provide patientswith CRC screening by a variety of methodswithin a single center.Coordination of Care and AdherenceAll members of the population should receivesome form of testing to improve CRC screeningoutcomes. Unfortunately, this is not yet the case.There are many reasons for this lack of adher-ence, but some patients remain concerned aboutvarious aspects of endoscopy. CTC presentspatients with an alternative, as we have no per-fect CRC screening modality. Before selectingthe method of CRC screening, it is desirable thateach patient has an understanding of the positiveand negative attributes of available methods.
  8. 8. 122 S. CarpenterThis type of communication requires patience,time, and resources. A formal consultative visitcan prove immensely beneficial. Primary carephysicians are perfectly suited to provide thisservice during routine visits, but due to issues oftime and complexity of primary care, a thoroughreview of options is not always possible. Thedata regarding CRC screening is far from static.Many primary care physicians are not fullyversed about the sensitivity and specificity of OCand CTC in asymptomatic patients or the propersurveillance intervals for adenomas. Manypatients are interested in discussing the data andoptions, and Centers of Digestive Health are ide-ally suited to provide this expertise.Barriers that interfere with patient adherenceto CRC screening must be eliminated. Patientsare unlikely to accept devoting two differentdays to the CRC screening effort. A single cen-ter approach to CRC screening with a strongemphasis on providing the option of same dayOC, should a mucosal abnormality be identifiedon CTC, is optimal. On occasion, OC may notprovide complete colonic imaging due to tech-nical or anatomic concerns. Immediate avail-ability of CTC is desired from a patientconvenience perspective. However, same dayCTC and OC require careful schedule coordina-tion, providing adequate time for endoscopicdefinitive therapy when polyps are identified onCTC. Prompt interpretation of CTC data isrequired to limit patient inconvenience. It isunlikely that patients will embrace an approachwherein OC follows CTC by more than 1 or 2 h.Furthermore, colonic preparation quality datasuggest that if OC occurs more than 4 h afterCTC, suboptimal colonic preparation can beexpected. This could adversely affect theefficacy of OC. Excellent communicationbetween the CTC interpreter and endoscopist isexpected. CRC screening centers will need toprospectively follow quality parameters suchfalse-negative and false-positive results of CTCand OC. Centers of Digestive Health may effec-tively follow the quality of patient care whileproviding comprehensive CRC screeningoptions using the modality selected by thepatient and their personal physician.It is important that patients adhere to follow-uprecommendations after a polyp is detected.Gastroenterologists are well versed in the appro-priate follow-up intervals for surveillance follow-ing removal of adenomas. It is still not clearwhether small polyps detected at CTC and notremoved may be safely followed with serial CTCover time. This remains an area of controversy.Patients will benefit from their personal physi-cian assisting them with this process. Follow-upof intracolonic and extracolonic abnormalitieswill require development of a patient healthmaintenance profile. A digestive center databasecould ensure that patients are contacted in subse-quent years when due for repeat CRC screening,be it by CTC or OC. Extracolonic abnormalitieswill require careful attention, and this is best donebetween patients and their personal physicians.Worrisome E3 findings may require further diag-nostic planning. E4 findings, such as hepatocel-lular carcinoma, cirrhosis, or large abdominalaortic aneurysms, will likely require definitivetherapy. It is important that patients adhere, notonly to the recommendations regarding polypmanagement, but also to diagnostic or therapeu-tic plans for extracolonic findingsEffective Integration of CTC and OCImplementation of an efficient CRC screeningprogram incorporating CTC requires coordina-tion of several key processes if availability ofsame-day OC is to be offered. Duncan et al.recently reviewed their database of all proceduresperformed from 2004 to 2010 [53]. In their patientpopulation at the National Naval Medical Center,11% of patients required OC due to positivefindings on CTC. Notably, 1,137 patients werereferred for OC after CTC, but only 130 patientsunderwent same-day OC. The average wait timefrom arrival for CTC to discharge after OC was348 min (range 178–684 min, SD 100 min,median 333 min). The process events that mustoccur for same-day OC after positive CTCinclude registration for CTC, performance ofCTC, radiologist CTC interpretation time, endos-copy unit registration time, OC preparation and
  9. 9. 1236 Integration of CTC into a CRC Screening Programcompletion time, and discharge time followingOC recovery.There are limited data on the extent thatwidespread implementation of CTC mightimpact upon OC volume at endoscopy centers.Using mathematical modeling based on data in2004, Hur et al. concluded that if CTC was usedas the primary modality for CRC screening, onecould expect a 22% decrease in OC demand.However, the polyp-size threshold utilized todefine a CTC test as positive (6 or 10 mm)significantly impacts this prediction [54]. In2008, Schwartz et al. noted that the initiation ofa screening CTC program at the University ofWisconsin did not result in a decrease in totalOC exams from 2004 to 2007 [55]. A meannumber of 10 patients per month were sent forOC after a positive CTC. In 2010, Benson et al.published the experience from the same centerin abstract form [56]. The mean per quarter totalnumber of OC exams performed increasedsignificantly from 1,104 in 2003 to 1,976 in2008 (P<0.001). They concluded that the initia-tion of a CTC screening program did not lead toa reduction in the number of OC exams per-formed. After the initiation of a CTC CRCscreening program, OC remained the predomi-nant screening modality. Importantly, Ladabaumet al. noted that if overall adherence to CRCguidelines is attained by a population, thenoverall OC volume increases, even with wide-spread utilization of CTC for screening [57]. Anexcellent working relationship between depart-ments of radiology, general internal medicine,and gastroenterology facilitates the effort [58].Coordination with pathology is also requiredfor effective integration.Adenoma detection ratesshould be followed for both radiologists andendoscopists. A peer review process for CTCinterpretation is necessary. Colonoscopic with-drawal times are yet another parameter that needsto be followed over time. The rate of E2 and E3findings on radiologic extracolonic interpretationshould be followed and compared to nationaldatabase statistics. There is no need to acquireand interpret data unless one is willing to actupon the information provided. Therefore, qual-ity improvement measures need to be in place toprovide meaningful feedback to physicians asthey strive to improve either their radiologic orendoscopic expertise. Following this feedback,performance measures should be continuouslyevaluated to ensure improvement and that thestandard of care is achieved. A carefully con-structed operating agreement within individualphysician practices or institutional policies andprocedures becomes crucial if an organizationidentifies and plans action regarding a physicianoutlier providing suboptimal patient care duringthe CRC screening effort.Financial ConsiderationsCTC reimbursement for CRC screening remainshighly variable. In May 2009, CMS published anoncoverage decision and stated, “The evidenceis inadequate to conclude that CT colonographyis appropriate for colorectal cancer screening”[59]. This decision had a considerable impact onthe adoption of screening CTC in the UnitedStates. Still, there are a number of health plansthat continue to reimburse for this procedure.There is considerable variance from state tostate with regard to coverage decisions.Clinicians must contact each provider to deter-mine the relative coverage of CTC for CRCscreening. This is a cumbersome task for anyorganization, and the administrative complexityalone has also impacted the widespread adop-tion of CTC.Over the past 7 years, there has been increasedadoption of CTC by US hospitals. McHugh et al.examined American Hospital Association annualsurveys and conducted interviews with severalhospital representatives [60]. There was modestincrease (13–17%) in the number of US hospitalsoffering CTC. Almost one-third of hospitals thatoffer CTC do not offer immediate OC after apositive CTC. Ideally, radiologists and gastroen-terologists work together to schedule the follow-up OC on the same day to avoid a secondcolon-cleansing preparation. Lack of coordina-tion or availability of on-site OC services, though,could increase the number of people lost tofollow-up after an initial CTC screen. Lack of
  10. 10. 124 S. Carpenterreimbursement for general screening and cost ofimplementation were major barriers thatprevented hospitals not offering CTC fromproceeding with implementation.The California Technology AssessmentForum (CTAF) assesses new and emerging med-ical technologies. In March 2009, the CTAFconcluded that CTC did not meet the technologycriterion for utilization as a screening test forCRC in average-risk individuals [61].Specifically, there were three main areas of con-cern. The CTAF was uncertain that there wassufficient evidence to conclude that CTC wouldimprove net health outcomes. The main concernhere was the unknown potential for harm relatedto radiation exposure. Secondly, the CTAFrequires that new technology must be asbeneficial as any established alternatives. A mainadditional concern here was the potential forsignificant adverse health outcomes related toextracolonic findings. “Many extracolonicfindings require additional evaluation, but areultimately clinically insignificant.” Lastly, docu-mented improvements in healthcare outcomesmust be attainable outside of the investigationalsetting. Mainly due to continued concerns aboutlong-term radiation exposure and extracolonicfindings, this criterion was not achieved in theCTAF’s opinion.The Institute of Technology Assessment atthe Massachusetts General Hospital evaluatedthe cost-effectiveness of CTC to aid CMS intheir recent decision regarding CTC for the aver-age-risk Medicare population [62]. Knudsenet al. concluded that CTC would be cost effec-tive if the reimbursement per scan is substan-tially less than that for OC. However, they didnote that if adherence to CRC screening wassubstantially improved that cost-effectiveness ofCTC also improved. The undiscounted numberlife-years gained from CTC screening rangedfrom 143 to 178 per 1,000 65-year-olds. Thisresult was slightly less than the number of life-years gained for OC every 10 years, whichranged from 152 to 185 per 1,000 65-year-olds.These findings were presented to the MedicareEvidence Development and Coverage AdvisoryCommittee in November 2008.ConclusionCTC may be utilized for CRC screening, andmodels have been developed in which gastroenter-ologists and radiologists work together to imple-ment effective CRC screening programs [63–65].Interpretation of CTC colonic images is classicallyperformed by radiologists, and although contro-versial, it has been proven that gastroenterologistsmay also attain competency in this area [66]. Thereremains continued concern about the impact ofradiation exposure and identification of extraco-lonic findings on patient well-being and healthcareexpenditure [67, 68]. Endoscopists are underincreased scrutiny with regard to the overall qual-ity of OC, and quality measures such as colonicpreparation, withdrawal time, and ADR must bemeasured and followed over time [69].Organizations that plan to integrate CTC and OCas options for CRC screening in their centers needto carefully measure quality parameters and makecontinuous quality improvement a top priority.References1. Rex DK, Johnson DA, Anderson JC, et al. AmericanCollege of Gastroenterology guidelines for colorectalcancer screening 2009.Am J Gastroenterol. 2009;104:739–50.2. Levin B, Lieberman DA, McFarland B, et al.AmericanCancer Society Colorectal Cancer Advisory Group;US Multi-Society Task Force; American College ofRadiology Colon Cancer Committee. Screening andsurveillance for the early detection of colorectal can-cer and adenomatous polyps, 2008: a joint guidelinefrom the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and theAmerican College of Radiology. Gastroenterology.2008;134:1570–95.3. Klabunde CN, Lanier D, Nadel MR, et al. Colorectalcancer screening by primary care physicians: recom-mendations and practices, 2006–2007. Am J PrevMed. 2009;37:8–16.4. Rex DK, Sledge G, Harper P, et al. Colonic neoplasiain asymptomatic persons with negative fecal occultblood tests: influence of age, gender, and family his-tory. Am J Gastroenterol. 1993;88:825–31.5. Lynch KL, Ahnen DJ, Byers T, et al. First-degree rela-tives of patients with advanced colorectal adenomashave an increased prevalence of colorectal cancer.Clin Gastroenterol Hepatol. 2003;1:96–102.
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