Christian Davis1, Jack Harrigan2, Mahak Chauhan, MD3, Reza Hejazi, MD4, Daniel Buckles, MD4, Mojtaba Olyaee, MD4, Kevin Kennedy, MS2, Rashna Madan, MD4, Ajay Bansal, MD5
1University of Kansas Health System, Fairway, KS; 2University of Kansas Health System, Kansas City, MO; 3University of Missouri, Kansas City, MO; 4University of Kansas Health System, Kansas City, KS; 5University of Kansas Health System / University of Kansas Cancer Center, Kansas City, KS
Introduction: Multigene panels are commonly used for genetic testing when Lynch syndrome is suspected. However, the data about the relative yield of Lynch vs. non-Lynch mutations are sparse.
Methods: In this retrospective, single-center study, all patients with a diagnosis of colon or uterine cancer between January 1, 2016 and June 30th, 2018 were included. The patients were identified using search in the pathology database for SNOMED codes. Additionally, the search results of SNOMED codes were tallied with the cancer center database to capture all patients with colon cancer. A structured RedCap electronic database was created to systematically abstract data about demographics, location and stage of colon cancer, PREMM5 scores, genetic testing and a detailed 3-generation family pedigree. After being screened for Lynch syndrome using immunohistochemical assays or PCR-based detection of microsatellite instability, patients with abnormal results underwent genetic testing using well-established multi-gene commercial assays. The yields of Lynch and non-Lynch syndromes were compared. Statistical comparisons were performed using Chi-square test for categorical variables and Student's t-test for numerical variables.
Results: A total of 737 participants (whites 84.1%, mean age of 62.7) were included. A diagnosis of Lynch syndrome was made in 21 of the 737 participants (2.85%). Non-Lynch mutations were detected in 12 of the 737 participants (1.63%). When colon and uterine cancers were analyzed separately, non-Lynch mutations were detected in 2.1% and 1.5% of participants respectively (Table 1). The non-Lynch genetic mutations detected included: APC, MAP syndrome, CHEK2, BRCA1, BRCA2, MUTYH, PALB2, AXIN2, SMARC4, and NTLH1.
Discussion: Germline testing has a significant yield of non-Lynch mutations in patients suspected to have Lynch syndrome. Our data support the current practice of multigene panels to define syndromic cancer risk.
Citation: Christian Davis; Jack Harrigan; Mahak Chauhan, MD; Reza Hejazi, MD; Daniel Buckles, MD; Mojtaba Olyaee, MD; Kevin Kennedy, MS; Rashna Madan, MD; Ajay Bansal, MD. P0227 - YIELD OF NON-LYNCH GENE MUTATIONS DURING TESTING FOR LYNCH SYNDROME. Program No. P0227. ACG 2019 Annual Scientific Meeting Abstracts. San Antonio, Texas: American College of Gastroenterology.