Advanced proximal neoplasia of the colon in average-risk adults.

BACKGROUND: Estimating risk for advanced proximal neoplasia (APN) based on distal colon findings can help identify asymptomatic persons who should undergo examination of the proximal colon after flexible sigmoidoscopy (FS) screening. OBJECTIVE: We aimed to determine the risk of APN by most advanced distal finding among an average-risk screening population. DESIGN: Prospective, cross-sectional study. SETTING: Teaching hospital and colorectal cancer screening center. PATIENTS: A total of 4651 asymptomatic persons at average risk for colorectal cancer aged 50 to 74 years (54.4% women [n = 2529] with a mean [± standard deviation] age of 58.4 ± 6.2 years). INTERVENTIONS: All participants underwent a complete colonoscopy, including endoscopic removal of all polyps. MAIN OUTCOME MEASUREMENTS: We explored associations between several risk factors and APN. Logistic regression was used to identify independent predictors of APN. RESULTS: A total of 142 persons (3.1%) had APN, of whom 85 (1.8%) had isolated APN (with no distal findings). APN was associated with older age, a BMI >27 kg/m(2), smoking, distal advanced adenoma and/or cancer, and distal non-advanced tubular adenoma. Those with a distal advanced neoplasm were more than twice as likely to have APN compared with those without distal lesions. LIMITATIONS: Distal findings used to estimate risk of APN were derived from colonoscopy rather than FS itself. CONCLUSION: In persons at average risk for colorectal cancer, the prevalence of isolated APN was low (1.8%). Use of distal findings to predict APN may not be the most effective strategy. However, incorporating factors such as age (>65 years), sex, BMI (>27 kg/m(2)), and smoking status, in addition to distal findings, should be considered for tailoring colonoscopy recommendations. Further evaluation of risk stratification approaches in other asymptomatic screening populations is warranted.