Associations between hepatitis B virus exposure and the risk of extrahepatic digestive system cancers: A hospital‐based, case–control study (SIGES)

Objectives This case–control study was aimed to investigate associations between HBV infection and extrahepatic digestive system cancers. Methods The patients of gastric, small intestinal, colonic, rectal, anal, biliary tract, and pancreatic cancers were retrospectively collected between 2016.5 and 2017.12. Simultaneously, the healthy controls were collected from the health check‐up registry, and cancer‐free status was confirmed based on medical...