Interaction between aflatoxin B1 and other risk factors in hepatocarcinogenesis

Abstract

Known causes of hepatocellular carcinoma (HCC) are chronic hepatitis B virus (HBV) infection; chronic hepatitis C virus (HCV) infection; dietary exposure to the fungal toxin, aflatoxin B1 (AFB1); cirrhosis, whatever its cause; the metobolic syndrome; hepatic iron overload and a number of rare inherited metabolic diseases. Of these, HBV and AFB 1 are the predominant risk factors in those resource-poor countries in Eastern and South-Eastern Asia, the Western Pacific islands, and sub-Saharan Africa that have the highest incidences of the tumour. Closer analysis reveals that the association between exposure to AFB1 and the development of HCC has been reported almost exclusively in countries in which chronic HBV infection is endemic. This is a chance finding, although the possibility that AFB1 is hepatocarcinogenic only in the presence of HBV has been mooted. Chronic HBV infection is more common in rural areas of sub-Saharan Africa and exposure to AFB1 is virtually confined to these areas. Black patients in sub-Saharan Africa and Chinese patients in the Asian-Pacific region with HCC are appreciably younger than patients elsewhere in the world, which could be explained, at least in part, by synergism between the hepatocarcinogenic properties of the two risk factors. Such an interaction may also contribute to the very high incidence of HCC in these regions and to its higher frequency in rural than in urban dwellers in the African sub-continent. © 2010 Springer-Verlag Berlin Heidelberg.