GUIDELINE ASGE guideline: colorectal cancer screening and surveillance This article is one of a series of statements discussing the use of gastrointestinal endoscopy in common clinical situations. The Standards of Practice Committee of the American Society for Gastrointestinal Endoscopy pre- pared this text. In preparing this guideline, a MEDLINE literature search was performed, and additional refer- ences were obtained from the bibliographies of the iden- tified articles and from recommendations of expert consultants. When little or no data exist from well- designed prospective trials, emphasis is given to results from large series and reports from recognized experts. Guidelines for appropriate use of endoscopy are based on a critical review of the available data and expert con- sensus. Further controlled clinical studies are needed to clarify aspects of this statement, and revision may be nec- essary as new data appear. Clinical consideration may justify a course of action at variance to these recommen- dations. This guideline replaces and supplements our previous document on colorectal cancer screening and surveillance. 1 INTRODUCTION Colorectal cancer (CRC) is the fourth most commonly diagnosed cancer and the second leading cause of can- cer-related deaths in the United States.2 Each year, ap- proximately 140,000 individuals are diagnosed with CRC and more than 50,000 will die from this malignancy. 2 The 5-year survival rate for early-stage cancers is greater than 90%, whereas the 5-year survival rate for those diag- nosed with widespread cancer is less than 10%. 3 There is indirect evidence that most cancers develop from adeno- matous polyps and that on average it takes 10 years for a !1 cm polyp to transform into invasive CRC. 4,5 Given the finding that adenomatous polyps are precursors to cancer and that polyps and early cancers are usually asymptomatic, there is a strong rationale to support screening asymptomatic individuals for early cancer detec- tion and prevention. RISK STRATIFICATION Approximately 30% of individuals harbor risk factors for CRC. 6 These risk factors include family or personal history of CRC or adenomatous polyps, personal history of inflam- matory bowel disease, and familial polyposis syndromes (including familial adenomatous polyposis [FAP] and he- reditary nonpolyposis colon cancer [HNPCC]). The other 70% of individuals are considered average risk. Screening strategies for average-risk individuals Average-risk individuals should be offered screening beginning at age 50 years. 7 The choice of modality for CRC screening along with the associated risks and benefits must be discussed between the practitioner and the indi- vidual patient 8 (Table 1). Colonoscopy. Colonoscopy is the preferred modality for CRC screening. Both cancer and premalignant neo- plasms can be accurately detected by colonoscopy. It of- fers the advantages of complete visualization of the entire colon, detection and removal of polyps, and diag- nostic sampling of cancers. Colonoscopy with polypec- tomy has been shown to significantly reduce the expected incidence of CRC by 76% to 90% in multiple co- hort studies. 9-11 In the National Polyp Study, patients who underwent colonoscopy with polypectomy had a 76% re- duction in CRC incidence compared with a general popu- lation registry. 9 The CRC incidence after colonoscopic polypectomy was reduced by 90% compared with the in- cidence in a cohort of patients who did not undergo poly- pectomy. 9 In a European cohort study of 1,693 patients who underwent colonoscopy with the removal of at least 1 adenoma R5 mm in size, the cancer incidence ratio was 0.34 compared to the incidence in a reference popula- tion. 10 In a study from Norway, 400 patients who were identified as having colon polyps on flexible sigmoidos- copy underwent colonoscopy with polypectomy and were followed prospectively over 13 years. 11 A control group of 399 patients who did not have any form of CRC screening was also followed prospectively. At 13 years, both groups underwent colonoscopy; the relative risk of cancer was 0.2 in the group that had prior colonoscopic polypectomy compared with the control group. There are currently no published studies specifically evaluating whether screening colonoscopy reduces Copyright ª 2006 by the American Society for Gastrointestinal Endoscopy 0016-5107/$32.00 doi:10.1016/j.gie.2006.02.002 546 GASTROINTESTINAL ENDOSCOPY Volume 63, No. 4 : 2006 www.giejournal.org