Five-year risk for advanced colorectal neoplasia after initial colonoscopy according to the baseline risk stratification: a prospective study in 2452 asymptomatic Koreans

ObjectivePostpolypectomy surveillance guidelines for colorectal cancer introduced the concept of ‘risk stratification’; however, few studies have been conducted for validation of its usefulness. The aim of this study was to assess the 5-year incidence of advanced neoplasia recurrence based on the risk stratification scheme of the guidelines and to identify its risk factors.MethodsA prospective study of surveillance colonoscopy after screening colonoscopy was carried out at the Seoul National University Hospital Healthcare System Gangnam Center. 3803 asymptomatic Koreans aged 50–69 were enrolled prospectively and 5-year cumulative adenoma rates were analysed according to three risk groups: normal (no baseline adenoma), low-risk (1–2 adenomas