Epstein-Barr virus associated gastric carcinoma at the United States-Mexico border: A single institution study.

440 Background: Globally, gastric cancer (GC) is the fourth most prevalent cancer, and the second leading cause of cancer related deaths. Epstein-Barr virus is implicated in the pathogenesis of 5-10% of gastric cancers. Based upon the results obtained from of the cancer genome atlas, EBV related GC is characterized by promoter hypermethylation, PIK3CA mutations (80%) and increased expression of PD-1 and PD-L1, making it an attractive target for molecularly targeted therapy and immunotherapeutic options. As such, a case can be made for routine testing for EBV in all GC patients. University medical center, El Paso is a tax payer funded safety net health system in El Paso country, TX. We conducted a pilot study to characterize the prevalence of EBV associated gastric cancer seen at this facility. Methods: After obtaining institutional review board (IRB) approval, we identified cases of GC that were diagnosed between January 1, 2008- and December 31-2017. A total of 104 cases were identified of which 17 samples were randomly selected. Pathology specimens were reviewed to identify grade, subtype (intestinal vs diffuse), degree of lymphocytic infiltration and presence/absence of H. pylori. Representative sections from archived tumors were used to perform in-situ hybridization to look for the presence of Epstein-Barr virus. Samples were analyzed using the Rembrandt In situ Hybridization and Detection Universal RISH& HRP Detection Kit for Epstein-Barr early RNA. Results: The median age of the 17 patients is 63 years with 59% being males. 95% self identified as Hispanic. 41% were smokers, 18% used alcohol. The mean BMI was 27.3. Forty one percent of gastric cancer cases were found in the body, 29% in the antrum, 12% in the cardia, and 6% in the fundus. Forty one percent of cases were Stage IV, 24% stage II, 17% Stage III and 17% Stage I. 95% of cases were high grade, 53% of them had signet ring features. 18% of samples were H. pylori positive. None of the seventeen samples tested positive for EBV. Conclusions: EBV does not seem to contribute significantly to the pathogenesis of gastric cancer in our local population. As such routine testing for EBV in all gastric cancer patients may not be a cost effective utilization of resources at our hospital.