Hepatitis C and hepatitis B in the etiology of hepatocellular carcinoma in the Japanese population.

We conducted case-control studies of hepatocellular carcinoma (HCC) and liver cirrhosis (LC) in relation to hepatitis C virus (HCV) and hepatitis B virus infection, involving 91 patients with HCC, 75 patients with LC who had no evidence of HCC, and 410 control subjects from the Japanese population. Serum antibody to HCV (anti-HCV) was detected by both enzyme-linked immunosorbent assay and recombinant immunoblot assay in 51, 51, and 3% of HCC, LC, and controls, respectively, whereas the corresponding prevalence of serum hepatitis B surface antigen (HBsAg) was 21, 11, and 2%, respectively. The relative risks (and 95% confidence intervals) for the presence of serum anti-HCV were estimated as 52.3 (23.9-114.3) for HCC and 64.4 (27.4-151.4) for LC. These values exceeded the relative risk of HCC (15.3) and that of LC (6.1) for positive serum HBsAg. Among male patients with HCC or LC, anti-HCV rates were very high in blood recipients (about 70%), heavy drinkers (46-62%), and those who had no identifiable risk factors (65-75%), indicating possible transmission of HCV via routes other than transfusion. No significant difference in anti-HCV status was observed between the HCC and LC groups. It was notable that anti-HCV was much less prevalent among HBsAg-positive patients with HCC or LC than among HBsAg-negative ones. There was a slight to moderate increase in HCC or LC risk among blood recipients and heavy drinkers after adjustment for anti-HCV status. These results indicate that, in Japan, the possible role of HCV infection in the etiology of HCC and LC is extremely large and seems to be more important than chronic hepatitis B virus infection.