Neoplasia detection via colonic surveillance among young individuals with MSH6 and PMS2-associated Lynch Syndrome.

Purpose: The age to initiate colonoscopy in MSH6/PMS2-associated Lynch Syndrome (LS) remains uncertain. Herein we characterize colonoscopy findings among young individuals with MSH6/PMS2-associated LS.

Methods: Retrospective review of a multi-institutional cohort of individuals with MSH6/PMS2-LS undergoing colonoscopy prior to age 50 was performed. Neoplastic lesions were defined as colorectal cancer (CRC), adenomas, or non-hyperplastic serrated lesions.

Results: Among 285 individuals [161 (56%) MSH6; 124 (44%) PMS2], 125 (44%) had a neoplastic finding inclusive of 53 (19%) with CRC [32 (20%) MSH6; 21 (17%) PMS2], with median age at CRC diagnosis of 38 and 38% reporting CRC family history. Among 824 available pooled procedures, there were 194 (24%) procedures with neoplastic lesions identified, including 21(2.6%) with advanced adenomas, 5 (0.5%) with advanced serrated lesions, and 34 (4.1%) with CRC. Among 122 procedures performed under age 30, 16 (13%) had neoplastic findings and 4 (3.3%) had CRC, of which all were found prior to LS diagnosis. Findings did not differ between MSH6 and PMS2 carriers.

Conclusions: Among individuals with MSH6/PMS2-associated LS undergoing early colonoscopy, neoplasia was common, even in those under 30. Current recommendations suggesting delayed initiation of surveillance among such patients may lead to missed preventive opportunities.