Two main areas of IIB research are the roles of EBV infection and of inflammation gene polymorphisms in the etiology of gastric cancer. We also study the descriptive epidemiology of this disease. The Branch is expanding collaborations with other DCEG investigations that will clarify the role of EBV in gastric cancers of different subsites and histologies in the Shandong and other completed gastric cancer studies. We have also analyzed cancer registration data from NCI's SEER program to examine effects of age at diagnosis as well as period and cohort trends.