NCI investigators are coordinating an international multi-center collaborative study of Epstein-Barr virus (EBV)-positive non-cardia gastric cancers (GC) from populations at high (e.g., Japan) and low (e.g., U.S.) risk for non-cardia GC. Contributing cohort and case-control studies provide previously collected epidemiologic data and submit biologic specimens for further testing. Cases of EBV-positive GC are compared to disease-free controls as well as to EBV-negative GC cases in case-control and case-case analyses. An initial report summarized previous data for 5,081 gastric cancer cases from 15 international populations with consistent laboratory testing for EBV. The ongoing consortium effort combines these cases with NCI and other datasets for pooled analyses of risk factors and prognosis of EBV-positive GC.