ABSTRACT
Primary hepatocellular carcinoma (HCC) is one of the most common human cancers worldwide, but it is a relatively rare disease in the western world. Only three human liver carcinogens are included in the International Agency for Research on Cancer human carcinogen list: aflatoxins, oral contraceptives, and vinyl chloride. All these chemicals were also found to induce liver tumors in rodents. Liver tumors are also induced by Thorotrast in clinical uses and by vinyl chloride in occupational exposures. Epidemiology studies have indicated that hepatocellular adenoma is associated with the use of oral contraceptives in women. Similar to tumors induced by oral contraceptives, hepatocellular adenomas induced by adrogenic and anabolic steroids may regress after discontinuation of steroid use or may progress to HCC. The mechanism of viral carcinogenesis is fundamentally different from chemical carcinogenesis. For aflatoxin and vinyl chloride, genotoxic mechanisms have been demonstrated by the formation of DNA adducts and specific gene mutations, especially in the p53 tumor-suppressor gene.
