Efficacy of Annual Colonoscopic Surveillance in Individuals With Hereditary Nonpolyposis Colorectal Cancer

Background & Aims Individuals with hereditary nonpolyposis colorectal cancer (HNPCC; Lynch syndrome) have a high risk for developing colorectal cancer (CRC). We evaluated the efficacy of annual surveillance colonoscopies to detect adenomas and CRCs. Methods In a prospective, multicenter cohort study, 1126 individuals underwent 3474 colonoscopies. We considered individuals from 3 groups of HNPCC families: those with a pathogenic germline mutation in a mismatch repair gene (MUT group), those without a mutation but with microsatellite instability (MSI group), and those who fufilled the Amsterdam criteria without microsatellite instability (MSS group). Results Compliance to annual intervals was good, with 81% of colonoscopies completed within 15 months. Ninety-nine CRC events were observed in 90 patients. Seventeen CRCs (17%) were detected through symptoms (8 before baseline colonoscopy, 8 at intervals >15 months to the preceding colonoscopy, and 1 interval cancer). Only 2 of 43 CRCs detected by follow-up colonoscopy were regionally advanced. Tumor stages were significantly lower among CRCs detected by follow-up colonoscopies compared with CRCs detected by symptoms ( P = .01). Cumulative CRC risk at the age of 60 years was similar in the MUT and MSI groups (23.0% combined; 95% confidence interval [CI], 14.8%–31.2%) but considerably lower in the MSS group (1.8%; 95% CI, 0.0%–5.1%). Adenomas at baseline colonoscopy predicted an earlier occurrence of subsequent adenoma (hazard ratio, 2.6; 95% CI, 1.7–4.0) and CRC (hazard ratio, 3.9; 95% CI, 1.7–8.5), providing information about interindividual heterogeneity of adenomas and kinetics of CRC formation. Conclusions Annual colonoscopic surveillance is recommended for individuals with HNPCC. Less intense surveillance might be appropriate for MSS families.