Colorectal cancer and advanced adenoma characteristics according to causative mismatch repair gene variant in Japanese colorectal surveillance for Lynch syndrome

Background The optimal interval of colonoscopy (CS) surveillance in cases with Lynch syndrome (LS), and stratification according to the causative mismatch repair gene mutation, has received much attention. To verify a feasible and effective CS surveillance strategy, we investigated the colorectal cancer (CRC) incidence at different intervals and the characteristics of precancerous colorectal lesions of LS cases. Methods This retrospective multicenter study was conducted in Japan. CRCs and advanced adenomas (AAs) in 316 LS cases with germline pathogenic variants ( path_ ) were analyzed according to the data of 1,756 registered CS. Results The mean time interval for advanced CRCs (ACs) detected via CS surveillance was 28.7 months (95% confidence interval: 13.8–43.5). The rate of AC detection within (2.1%) and beyond 2 years (8.7%) differed significantly ( p = 0.0003). AAs accounted for 43%, 46%, and 41% of lesions