Identifying Hereditary Gastric Cancer Predisposition In The Clinical Cancer Genomics Community Research Network

Genetic Cancer Risk Assessment (GCRA) clinical referral and testing guidelines are limited for individuals and families with gastric cancer. In part, this is due to a lack of knowledge regarding hereditary gastric cancer susceptibility. The Clinical Cancer Genomics Community Research Network registry includes over 15,000 families seen for GCRA at City of Hope and 45 other collaborating sites. The purpose of this research was to identify variants conferring inherited gastric cancer susceptibility for individuals and families in our registry without previously known genetic predisposition. Adult research participants from our IRB-approved registry with a DNA sample and a personal history of gastric cancer were selected. Those with a previously identified genetic predisposition were excluded (n = 8). In families with more than one eligible individual, the individual with earliest onset of disease was selected. All histologies were included (i.e., intestinal and diffuse adenocarcinomas, as well as, gastrointestinal stromal tumors). Of 47 eligible participants, 22 had previously uninformative clinical testing. Germline sequencing was completed using a novel 706 candidate cancer gene panel, which included genes involved in DNA damage response, cell cycle regulation, apoptosis, and the Fanconi anemia, mTOR, JAK-STAT, and RAS-MAPK pathways; known cancer susceptibility genes; and genes frequently mutated in gastric tumors (data from the Catalog of Somatic Variants in Cancer database). Based on 2015 American College of Medical Genetics and Genomics and the Association for Molecular Pathology Standards and Guidelines, 18 out of 47 research participants had pathogenic or likely pathogenic germline variants. Of the 18, 11 had a first- or second-degree relative with gastric cancer. Variants were identified in established cancer susceptibility genes, such as BRCA2, BRIP1, RAD51C, ATM, FLCN, as well as in genes from rare autosomal recessive conditions, such as FANCC. In conclusion, using a 706 gene panel to test a GCRA cohort, we were able to identify potentially pathogenic variants in 38% of participants with gastric cancer, with nearly half of these variants in clinically actionable genes. The variants identified in this study will need to be further evaluated using segregation studies, tumor studies, and in larger cohorts to establish causality. Citation Format: Thomas P. Slavin, Kai Yang, Sharon Sand, Tanya Chavez, Danielle Castillo, Joseph Herzog, Ilana Solomon, Christina Rybak, Mariana Niell-Swiller, Bita Nehoray, Aaron Adamson, Kathleen Blazer, Susan Neuhausen, Jeffrey Weitzel, Clinical Cancer Genomics Community Research Network. Identifying hereditary gastric cancer predisposition in the clinical cancer genomics community research network. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2551.