Colorectal Neoplasia Detection Rates in Lynch Syndrome

The expected and optimal adenoma detection rate (ADR) is not well characterized in Lynch syndrome (LS). The aim of this study is to determine the ADR, the overall colorectal neoplasia detection rate (CNDR), proximal serrated detection rate (PSDR), and CRC detection rate (CRCDR) in an LS cohort.

A retrospective study was performed of individuals with LS who were evaluated at a single tertiary care center from May 2001 to September 2023 (n = 542). Data from procedure and pathology reports were collected along with relevant demographic, clinical history, and family history data. Fisher's exact test and the Kruskal-Wallis test were used to assess factors associated with colorectal neoplasia.

Amongst 542 individuals with LS, 352 met the inclusion criteria, and their 1296 colonoscopies/sigmoidoscopies were used for analysis. The cohort was primarily female (64.5%), white (87.5%), and privately insured (76.1%), with a near even distribution across genotypes. CNDR was 27.9%, ADR was 21.4%, PSDR was 7.7%, and CRCDR was 1.5%. Advanced age, Medicare insurance, prior colonic resection, and prior history of non-CRC were significantly associated with an increased CNDR and ADR (p < 0.05). PSDR remained constant with age. There was no association with genotype, biological sex, race, smoking, BMI, aspirin use, nor family history.

Despite frequent colonoscopies/sigmoidoscopies, individuals with LS maintain a high rate of colorectal neoplasia, primarily driven by increased detection of adenomas with advancing age. Neoplasia rates may serve as helpful "ballpark rates" for endoscopists performing colonoscopies/sigmoidoscopies in LS. However, further studies need to determine whether neoplasia rates are predictive of CRC risk and outcomes in LS.