Source State Key Laboratory of Oncology in South China, Guangzhou 510060, China; Department of Medical Oncology, Sun Yat-sen University Cancer Center, Guangzhou 510060, China.

Little is known about the role of association between ABO blood type and risk of pancreatic cancer develops through effects on hepatitis B viral (HBV) infection. This study aimed to determine whether joint ABO blood type and HBV infection could increase the risk for pancreatic cancer. A total of 645 patients with pancreatic adenocarcinoma and 711 age-, and sex-matched individuals who had nonmalignant diseases treated at the Sun Yat-sen University Cancer Center in China were retrospectively analyzed. Blood samples were tested for ABO blood type and hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (anti-HBs), hepatitis B e antigen (HBeAg), hepatitis B e antibody (anti-HBe) and hepatitis B core antibody (anti-HBc). Multivariable unconditional logistic regression analysis was used to estimate adjusted odds ratios [AORs] and 95% confidence interval [CI]. Multivariable analysis with adjustment for risk factors showed that A blood type, HBsAg-positive/anti-HBc-positive, anti-HBs-positive/anti-HBc-positive were significantly associated with pancreatic cancer. The estimated AORs (95% CI) were as follows: A blood type, 1.425 (1.071 to 1.894), HBsAg-positive/anti-HBc-positive, 1.610 (1.125 to 2.304), anti-HBs-positive/anti-HBc-positive, 1.526 (1.159 to 2.011). The effect of A blood type significantly modified the risk of pancreatic cancer among subjects with anti-HBc-positive (AORs = 1.882, 95% CI, 1.284 to 2.760). In our study, we reported an association between A blood type, infection with HBV and pancreatic cancer risk. Moreover, we found a synergism between A blood type and HBV infection in the development of pancreatic cancer.