Hepatocarcinogenesis.

Hepatocellular carcinoma (HCC), the most frequent malignant tumour of the liver, is the commonest cancer occurring in males in the world. The annual incidence of the disease worldwide is estimated to be one million cases. There are variations in its geographical distribution. It tops the list of malignancies amongst males in sub-saharan Africa; it is the second most common cancer in Southeast Asia, including Hong Kong, and ranks third amongst males in China. It is relatively rare in America, Europe North Africa, and the Middle East. During the last 15 years, epidemiologic and laboratory investigations have established a strong and specific association between chronic hepatitis B virus (HBV) infection and HCC. Hepatic cirrhosis is another major aetiologic factor incriminated. In areas with a low incidence of HCC, cirrhosis due to alcohol may be a relatively more important predisposing factor. Chronic non-A, non-B hepatitis (NANBH) infection has now been incriminated as a cause of HCC, especially in Japan. Other environmental factors, particularly chemical carcinogens such as Aflatoxin, smoking, genetic predisposition and sex hormones may also act to promote hepatocarcinogenesis. The exact mechanisms of neoplastic transformation, however, are still far from understood. The following factors are discussed in detail: 1. HBV infection 2. Cirrhosis 3. NANBH infection 4. Aflatoxin B1 5. Cigarette smoking 6. Alcohol A number of less important associated diseases are also listed in Table I. At the end of this paper, a tentative scheme for hepatocarcinogenesis has been proposed and the methods for prevention is discussed in light of the risk factors considered.