Colonoscopy findings and polyp pathology in CHEK2 carriers: a single center experience

Checkpoint kinase 2 is a moderate-penetrance cancer susceptibility gene associated with increased colorectal cancer risk. Recent guideline updates recommend average-risk colorectal cancer screening for carriers; however, real-world colonoscopy data remain limited. We performed a retrospective review of individuals with confirmed pathogenic or likely pathogenic checkpoint kinase 2 variants identified through an institutional hereditary cancer registry from 2011 to 2024. Colonoscopy and pathology reports were analyzed for demographics, cancer history, bowel preparation quality, and polyp characteristics including number, size, histology, and location. Among 144 patients undergoing 154 colonoscopies, median age at examination was 54 years. Polyps were identified in 51% of patients. Tubular adenomas were most common (28.6%), followed by hyperplastic polyps (18.3%) and sessile serrated lesions (10.4%). Advanced neoplasia, defined using conventional advanced adenoma-based criteria (size > 1 cm, villous features, high-grade dysplasia, or classified as intramucosal or invasive carcinoma) as well as including sessile serrated lesions ≥1 cm, were identified in 4.6%. Polyps measuring at least 1 centimeter were observed in 7.1%, and colorectal cancer was diagnosed in 1.3%. Proximal-only polyps were identified in 22.1% of examinations. Detection of tubular adenomas and proximal lesions increased with successive colonoscopies. This single-center experience demonstrates a moderate polyp burden with low rates of advanced neoplasia and colorectal cancer, supporting current recommendations for average-risk screening while highlighting the relevance of careful proximal examination.