Smoking as a risk factor in hepatocellular carcinoma. A case-control study in southern African blacks.

Two hundred forty southern African black patients with hepatocellular carcinoma and control subjects matched for race, sex, age, and urban or rural background were questioned about their smoking habits. Patients with hepatocellular carcinoma were not more likely to smoke or to smoke heavily than the control subjects. This was also true of the subgroups: men and women, and urban and rural background. There was a slightly increased relative risk associated with smoking in all patients who showed no serum markers of current or past hepatitis-B virus infection and in patients older than 50 years who did not have markers of current or past hepatitis-B virus infection. However, this was not statistically significant, and was not supported by a linear trend, the risk in heavy smokers being less than 1. Rural black patients, who have a higher incidence of hepatocellular carcinoma than urban black patients, smoked less than their urban counterparts. We conclude that smoking is not an unqualified risk factor for hepatocellular carcinoma in southern African black patients. There may, however, be a trend toward smoking playing an etiologic role in patients without hepatitis-B virus infection, especially in older patients.