Incidence and prevalence of advanced colorectal neoplasia in Lynch syndrome

Abstract

Ynch syndrome (LS) is the commonest hereditary cause of colorectal (CRC) and endometrial cancer (EC). Colonoscopy reduces CRC in LS but the protection is variable. We assessed prevalence and incidence of neoplasia in LS during surveillance colonoscopy in the United States (US) and factors associated with advanced neoplasia. LS patients undergoing ≥ 1 surveillance colonoscopy and no personal history of invasive CRC or colorectal surgery were included. Prevalent and incident neoplasia was defined as occurring < 6 months before and ≥ 6 months after germline diagnosis of LS. We assessed advanced adenoma (AA), CRC and the impact of mismatch repair pathogenic variant (PV) and typical LS cancer history (personal history of EC and/or family history of EC/CRC) on outcome. 132 patients (inclusive of 112 undergoing prevalent and incident surveillance) were included. The median exam interval and duration of prevalent and incident surveillance was 0.88 and 1.06 and 3.1 and 4.6 years, respectively. Prevalent and incident AA were detected in 10.7% and 6.1% and CRC in 0.9% and 2.3% of patients, respectively. All incident CRC occurred in MSH2 and MLH1 PV carriers and only 1 (0.7%) while under surveillance in our center. AA were detected in both LS cancer history cohorts, and represented in all PVs. In a US cohort of LS, advanced neoplasia rarely occurs over annual surveillance. CRC was diagnosed only in MSH2/MLH1 PV carriers. AA occur regardless of PV or LS cancer history. Prospective studies are warranted to confirm our findings.