Liver cancer: descriptive epidemiology and risk factors other than HBV and HCV infection

The incidence of liver cancer is high in all low-resource regions of the world, with the exception of Northern Africa and Western Asia. The estimated worldwide number of new cases of liver cancer in 2002 is 600,000, of which 82% are from developing countries. Given the poor survival from this disease, the estimated number of deaths is similar to that of new cases. Hepatocellular carcinoma (HCC) is the main form of liver cancer. A part from chronic infections with Hepatitis B and Hepatitis C viruses, which are the main causes of HCC, contamination of foodstuff with aflatoxins, a group of mycotoxins produced by the fungi Aspergillus flavus and Aspergillus parasiticus, is an important contributor to HCC burden in many low-income country. Alcoholic cirrhosis is an important risk factor for HCC in populations with low prevalence of HBV and HCV infection, and the association between tobacco smoking and HCC is now established. Diabetes is also related to an excess risk of HCC and the increased prevalence of overweight and obesity likely contributes to it. The second most important type of liver cancer is cholangiocarcinoma, whose main known cause is infestation with the liver flukes, Opistorchis viverrini and Clonorchis sinensis, which is frequent in some areas in South-East Asia. Angiosarcoma is a rare form of liver cancer whose occurence is linked to occupational exposure to vinyl chloride.