S322 Colonoscopy Findings in Patients With a Germline Pathogenic Variant in CDH1

Introduction: Germline pathogenic variants (PV) in CDH1 predispose to hereditary diffuse gastric cancer and lobular breast cancer. There is no data on the risk of colorectal neoplasia in carriers of CDH1 pathogenic variants. Our aim is to investigate the colonoscopy findings in patients with a pathogenic variant in CDH1 undergoing colorectal cancer screening with colonoscopy. Methods: This IRB-approved study identified patients with germline PV in CDH1 throughout the Cologene™ database in the David G. Jagelman Inherited Colorectal Cancer Registries. The electronic medical record was used to obtain information, including demographic characteristics, personal and family history of cancer, and colonoscopy findings, including adenomas, advanced adenomas (≥3 adenomas, or an adenoma ≥ 10 mm, or with villous features or high-grade dysplasia), and invasive colorectal cancer (CRC). Results: This IRB-approved study identified patients with germline PV in CDH1 throughout the Cologene™ database in the David G. Jagelman Inherited Colorectal Cancer Registries. The electronic medical record was used to obtain information, including demographic characteristics, personal and family history of cancer, and colonoscopy findings, including adenomas, advanced adenomas (≥3 adenomas, or an adenoma ≥ 10 mm, or with villous features or high-grade dysplasia), and invasive colorectal cancer (CRC). (Table) Conclusion: In our small cohort of mostly female carriers of pathogenic variants in CDH1 undergoing screening colonoscopy, we found an early onset colon cancer and a high incidence of early-onset adenomas and advanced adenomas. We suggest colonoscopy be considered for patients with CDH1 PV at the age of 40 years or 10 years younger than the earliest age of CRC in an FDR if under the age of 60 at diagnosis. Table 1. - Data is presented as median and quartiles [25th, 75th percentiles] or frequency (percent) Factors Number of Carriers=34 Age (years) 52.6 [48.7;60.7] Gender: Female/Male 24 (70.6%)/ 10 (29.4%) Personal History of Gastric Cancer/Breast Cancer 16 (47.1%)/13 (38.2%) Family History of Colorectal Cancer or Advanced Adenoma 11 (32.4%) Age at 1st colonoscopy (years) 50.1 [46.7;57.8] Number of colonoscopies per patient # 1 24 (71%) # 2 7 (21%) # 3 or more 3 (9%) Patients with Polyps 18 (53%) Age at First Polyp (years) 51.6 [49.4;61.8] Cumulative Number of Polyps 1.00 [0.00;1.00] Patients with Hyperplastic Polyps 4 (12%) Patients with Tubular Adenomas < 10 mm 12 (35%) Patients with Advanced Adenomas# Tubulovillous/Villous adenoma# High-Grade Dysplasia 4 (12%)3 (9%)1 (3%) Patients with CRC 1 (3%) Age at first Tubular Adenoma (years) 54.6 [47.4;63.3] Age at first Advanced Adenoma (years) 54.1 [50.4;58.0] Age at CRC (years) 49.2