[Interaction among the relative risk factors of primary liver cancer in a case-control study].

This paper evaluates the combined effect of HBsAg, drinking water and aflatoxin B1 (AFB1) on the primary hepatocellular carcinoma (PHC) in a case-control study which was carried out in Fusui, Guangxi. We used relative risk model (from subadditive to supermultiplicative) to fit the relationship. The results showed that the combined effect of HBsAg infection and drinking pond-ditch water is nearly multiplicative, and the combined effect of HBsAg infection and AFB1 intake as well as drinking pond-ditch water and AFB1 intake were nearly additive.