Epidemiology of hepatocellular carcinoma

Although rare in Canada and the United States, hepacocellular carcinoma (HC C) ranks as the eighth most common cancer in the world. High-risk regions a re East and Southeast Asia, and sub-Saharan Africa. Independent of race and geography, rates in men are at least two to three times those in women; th is sex ratio is more pronounced in high-risk regions. Rates of HCC in the U nited States have increased by 70% over the past two decades. Registry data in Canada and Western Europe show similar trends. In contrast, the inciden ce of HCC in Singapore and Shanghai, China, both high-risk regions, has dec lined steadily over the past two decades. Among white and black Americans, there is an inverse relationship between social class status and HCC incide nce Chronic infection by the hepatitis B virus (HBV) is by far the most imp ortant risk factor for HCC in humans. It is estimated that 80% of HCC world wide is etiologically associated with HBV. In the United States, although t he infection rate in the general population is low, HBV is estimated to acc ount for one in four cases of HCC among non-Asians. Chronic infection by th e hepatitis C virus is another important risk factor for HCC in the United States; however, this virus is believed to play a relatively minor role in the development of HCC in Africa and Asia. Dietary aflatoxin exposure is an important codeterminant of HCC risk in Africa and parts of Asia. In Canada and the United States, excessive alcohol intake, cigarette smoking and ora l contraceptive use in women also are risk factors for HCC.