Epidemiology Endemic hot spots occur in areas of China and sub-Saharan Africa, which are associated with both high endemic hepatitis B carrier rates and mycotoxin contamination of foodstuffs, stored grains, drinking water, and soil. Environmental factors are important; Japanese in Japan have a higher incidence than those living in Hawaii, who in turn have a higher incidence than those living in California. Etiologic Factors Chemical Carcinogens Probably the best-studied and most potent ubiquitous natural chemical carcinogen is a product of the Aspergillus fungus, called aflatoxin B1. This mold and aflatoxin product can be found in stored grains in hot, humid places, where. | Chapter 088. Hepatocellular Carcinoma Part 2 Epidemiology Endemic hot spots occur in areas of China and sub-Saharan Africa which are associated with both high endemic hepatitis B carrier rates and mycotoxin contamination of foodstuffs stored grains drinking water and soil. Environmental factors are important Japanese in Japan have a higher incidence than those living in Hawaii who in turn have a higher incidence than those living in California. Etiologic Factors Chemical Carcinogens Probably the best-studied and most potent ubiquitous natural chemical carcinogen is a product of the Aspergillus fungus called aflatoxin B1. This mold and aflatoxin product can be found in stored grains in hot humid places where peanuts and rice are stored in unrefrigerated conditions. Aflatoxin contamination of foodstuffs correlates well with incidence rates in Africa and to some extent in China. In endemic areas of China even farm animals such as ducks have HCC. The most potent carcinogens appear to be natural products of plants fungi and bacteria such as bush trees containing pyrrollizidine alkaloids as well as tannic acid and safrole. Pollutants such as pesticides and insecticides are known rodent carcinogens. Hepatitis Both case-control and cohort studies have shown a strong association between chronic hepatitis B carrier rates and increased incidence of HCC. In Taiwanese male postal carriers who were hepatitis B surface antigen HBsAg -positive a 98-fold greater risk for HCC was found compared to HBsAg-negative individuals. The incidence of HCC in Alaskan natives is markedly increased related to a high prevalence of HBV infection. HBV-based HCC may arise from rounds of hepatic destruction with subsequent proliferation and not necessarily from frank cirrhosis. The increase in Japanese HCC incidence rates in the past three decades is thought to be from hepatitis C. A large-scale intervention study sponsored by the World Health Organization WHO is currently underway in Asia involving
