Dietary risk factors for primary hepatocellular carcinoma.

Primary hepatocellular carcinoma (PHC) is among the most common forms of cancer, on a global basis. Incidence of the disease varies greatly in different areas of the world, suggesting involvement of environmental etiological factors, and much research has been devoted to their identification. Because many organic chemicals have been shown to have the capability of inducing PHC in animals, they have been extensively studied with respect to their possible significance as etiologic agents for PHC in man. Particular emphasis has been placed on aflatoxins because of their widespread occurrence as food contaminants and potency as liver carcinogens in a large number of experimental animals, including subhuman primates. Epidemiologic surveys have revealed a strong statistical correlation between aflatoxin ingestion and incidence of PHC in several areas of Africa and Asia. The IARC has recently determined the combined experimental and epidemiological information to be sufficient to designate aflatoxins as human carcinogens. The importance of hepatitis B virus (HBV) infection as a risk factor for PHC is extensively discussed by other authors in this journal issue. Prospective epidemiological studies have shown a high incidence of PHC among HBV carriers in HBV-endemic areas. Clinical studies have also shown that most PHC patients are carriers of the hepatitis B surface antigen and have chronic active hepatitis. Recently, HBV sequences have been found to be integrated into the liver cell genome in some, but not all, patients with chronic hepatitis or PHC. This evidence has identified HBV as a major etiological factor for PHC in certain populations, particularly in Taiwan and the People's Republic of China.(ABSTRACT TRUNCATED AT 250 WORDS)