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Electronic letters published:
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Predictive accuracy of the postpolypectomy guidelines - authors' reply
Post-polypectomy Surveillance Guideline
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Adeyinka O. Laiyemo, MD, MPH National Cancer Institute, Elaine Lanza, PhD and Arthur Schatzkin, MD, DrPH
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laiyemoa{at}mail.nih.gov Adeyinka O. Laiyemo, et al.
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To the editors, We agree with Drs. Rex and Winawer that a single study is unlikely to be definitive, especially when, as they suggest, variability in clinician judgment influences the identified predictors of higher risk for advanced adenoma. We did not, however, recommend shortening the interval of surveillance colonoscopy for the low-risk category (1). In our study, the advanced adenoma recurrence rate was 9% among the high-risk and 5% among the low-risk category at 4 years. The c-statistics from multivariate models incorporating demographic and lifestyle factors with adenoma characteristics indicated that there was not much discrimination between the 2 risk groups. Although, these finding may be interpreted as meaning we should screen both groups at 3 years, they could just as well be viewed as suggesting we should extend the surveillance interval for both groups to 5 years. Given the cost and risk associated with colonoscopic surveillance, the challenge becomes developing interval surveillance recommendations based on risk categorization schemes with greater predictive capacity. Combining the data from completed and ongoing adenoma trials and observational studies may help achieve this goal, especially if we conduct multivariate analyses incorporating demographic and lifestyle information along with adenoma characteristics. Whether additional colonoscopy- adenoma studies are needed to achieve the desired predictability for risk assignment remains to be seen. Sincerely, Adeyinka O. Laiyemo, MD, MPH Cancer Prevention Fellowship Program, Office of Preventive Oncology and Division of Cancer Prevention, National Cancer Institute Elaine Lanza, PhD Laboratory of Cancer Prevention, Center for Cancer Research, National Cancer Institute Arthur Schatzkin, MD, DrPH Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute References 1. Laiyemo AO, Murphy G, Albert PS, Sansbury LB, Wang Z, Cross AJ, et al. Postpolypectomy surveillance guidelines: predictive accuracy for advanced adenoma at 4 years. Ann Intern Med. 2008;148:419-26. [PMID: 18347350]. Conflict of Interest:None declared |
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Douglas K. Rex, MD Indiana University Hospital, Sidney J. Winawer, Memorial Sloan-Kettering Cancer Center, NY, NY
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drex{at}iupui.edu Douglas K. Rex, et al.
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To the editors, Laiyemo et al were critical of the discriminatory value of current post-polypectomy surveillance guidelines (1). The history of post- polypectomy practice has been to expand intervals, first from 1 to 3 years, then from 3 to 5 years in the cohort considered at lowest risk. The rationale for interval expansion is that surveillance has risk, cost, and less value in preventing cancer than baseline clearing examinations (2). We are concerned that colonoscopists will react to Laiyemo et al’s findings by shortening intervals. Several factors warrant comment. First, the guideline was based on the totality of literature relating baseline colonoscopy findings to subsequent advanced neoplasia (3). Contrary to the accompanying editorial claiming that the guideline is based on 5 studies, we identified and summarized 12 relevant studies (3). No predictor of higher risk was found in all studies (3). This may reflect that multiplicity of baseline adenomas depends on efficacy of clearing (4), that polyp size is subject to endoscopist interpretation, and that villous elements and high grade dysplasia are subject to marked interobserver variation. Thus, no single study (1) would be expected to confirm each risk factor in the guideline or to represent a definitive study. Second, the guideline does not recommend major differences in follow-up for higher vs lower risk baseline findings, consistent with mixed evidence. Thus, patients with higher risk findings are recommended to undergo colonoscopy at 3 years, and the lower risk group at 5 to 10 years. Most of the latter group undergoes colonoscopy at <= 5 years in the U.S. Third, while advanced adenomas are an accepted surrogate endpoint, they do not kill people. Shortening intervals from 5 years to 3 years to detect a 5% incidence of advanced adenomas in a lower risk cohort will not clearly reduce cancer incidence or deaths at acceptable cost and risk. The principle limitation to the effectiveness of any surveillance guideline is variability between endoscopists in effectiveness of baseline clearing (4,5). We emphasized the importance of quality baseline examinations in the guideline (3). We believe that much more can be gained in efficacy, safety and cost reductions by improving the quality of baseline examinations than by shortening post-polypectomy intervals in patients for whom the totality of the literature indicates a low risk of advanced neoplasia over 5 years or longer. Sincerely, Douglas K Rex M.D., FACP, Indiana University School of Medicine, Indianapolis, Indiana Sidney J Winawer, M.D., FACP, Memorial Sloan-Kettering Cancer Center, New York, New York References: 1. Laiyemo AO, Murphy G, Albert PS, Sansbury LB, Wang Z, Cross AJ, Marcus PM, Caan B, Marshall JR, Lance P, Paskett ED, Weissfeld J, Slattery ML, Burt R, Iber F, Shike M, Kikendall JW, Lanza E, Schatzkin A. Postpolypectomy colonoscopy surveillance guidelines: predictive accuracy for advanced adenoma at 4 years. Ann Intern Med 2008;148:419-26. 2. Zauber A, Winawer SJ, Lansdorp-Vogelaar I, van Ballegooijen M, O’Brien MJ. Effect of initial polypectomy versus surveillance polypectomy on colorectal cancer mortality reduction: micro-simulation modeling of the National Polyp Study. Am J Gastroenterol 2007;102:S558. 3. Winawer SJ, Zauber AG, Fletcher RH, Stillman JS, O'Brien MJ, Levin B, Smith RA, Lieberman DA, Burt RW, Levin TR, Bond JH, Brooks D, Byers T, Hyman N, Kirk L, Thorson A, Simmang C, Johnson D, Rex DK. Guidelines for colonoscopy surveillance after polypectomy: a consensus update by the US Multi-Society Task Force on Colorectal Cancer and the American Cancer Society. Gastroenterology 2006;130:1872-85. 4. Chen SC, Rex DK. Endoscopist can be more powerful than age and male gender in predicting adenoma detection at colonoscopy. Am J Gastroenterol 2007;102:856-61. 5. Barclay RL, Vicari JJ, Doughty AS, Johanson JF, Greenlaw RL. Colonoscopic withdrawal times and adenoma detection during screening colonoscopy. N Engl J Med 2006;355:2533-41. Conflict of Interest:None declared |
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