RESUMEN
Objective To investigate the influencing factors for liver cancer by gender in Shunde region, and to explore the potential interactions among influencing factors for liver cancer in males. Methods The relative excess risk of interaction (RERI) and other indices were used to evaluate the pair-wise interaction, and the classification and regression tree (CART) model was applied to explore the potential multi-factors interaction. Results This study included 1 037 male cases and 1 069 controls, together with 166 female cases and 185 controls. Chronic hepatitis B virus infection (CHB) and family history of liver cancer were significantly associated with increased risk of liver cancer both in males and females (both P<0.001). In males, positive additive interactions were observed between CHB and smoking or alcohol drinking, as well as between smoking and drinking. The RERI for CHB and smoking was 121.90(95% CI：52.85%-190.95%). Negative additive interactions were observed between exercise and CHB or smoking. Further, the CART analysis suggested that the CHB males who smoked and drank alcohol had the highest risk of liver cancer. Conclusions CHB and family history of liver cancer are important risk factors for liver cancer in both males and females. CHB, smoking, and alcohol drinking synergistically promote the incidence of liver cancer for males. Exercise can antagonize the hepatocarcinogenic effect of CHB and smoking.