Neoplasia Detection Through Colonic Surveillance Among Young Individuals With MSH6 / PMS2 -Associated Lynch Syndrome.

[INTRODUCTION] The age to initiate colonoscopy in MSH6 / PMS2 -associated Lynch syndrome (LS) remains uncertain. In this study, 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 -associated LS undergoing colonoscopy before the age of 50 years was performed. Neoplastic lesions were defined as colorectal cancer (CRC), adenomas, or nonhyperplastic 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 years and 38% reporting CRC family history. Among 824 available pooled procedures, there were 194 procedures (24%) 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 the age of 30 years, 16 (13%) had neoplastic findings and 4 (3.3%) had CRC, of which all were found before LS diagnosis. Findings did not differ between MSH6 and PMS2 carriers.

[DISCUSSION] Among individuals with MSH6/PMS2 -associated LS undergoing early colonoscopy, neoplasia was common, even in those aged younger than 30 years. Current recommendations suggesting delayed initiation of surveillance among such patients may lead to missed preventive opportunities.