The role of infection by Opisthorchis viverrini, hepatitis B virus, and aflatoxin exposure in the etiology of liver cancer in Thailand: a correlation study

Article Abstract:

The two most common forms of primary liver cancer are hepatocellular carcinoma and cholangiocarcinoma. Hepatocellular carcinoma arises from liver cells themselves, while cholangiocarcinoma arises from cells lining the ducts that carry bile from the liver. Hepatocellular carcinoma is associated with chronic infection with hepatitis B, exposure to the toxic substance aflatoxin (which occurs in some molds) and other factors, such as alcohol consumption. In the United States, hepatocellular carcinoma is by far the more common type of liver cancer; only 7.7 percent of liver cancers are cholangiocarcinoma in the US. In contrast, cholangiocarcinoma is quite common in some parts of Southeast Asia. In the northeastern portion of Thailand, more than 60 percent of liver tumors are cholangiocarcinoma. In Thailand, liver cancer is the most common cancer among men and the third most common among women. Investigators have noticed that the geographical distribution of cholangiocarcinoma seems to parallel that of some liver flukes, parasitic flatworms which infect the liver. A study was conducted in five different regions of Thailand to compare the exposure to different risk factors with the incidence of the two main types of liver cancer. The results showed that there was little difference among the five regions in the exposure to aflatoxin or the prevalence of chronic hepatitis B infection. The rate of hepatocellular carcinoma was also similar among the geographical regions, as might be expected from the similarity of the risk factor exposure. However, the researchers found that the rate of cholangiocarcinoma was greatest in regions with high levels of exposure to a local liver fluke known as Opisthorchis viverrini. The rate of cholangiocarcinoma in Bangkok, where the rate of liver fluke infection is low, is about 36 percent that of Thailand as a whole. In contrast, the rate of cholangiocarcinoma in the Ubon region, where O. viverrini is endemic, is 334 percent that of Thailand as a whole. These results suggest that liver parasites play an important role in the development of cholangiocarcinoma, and that reductions in parasite infection in some rural areas of Thailand would seem likely to result in reductions in the rate of this liver cancer as well. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Thailand, Helminths, Aflatoxins, Gallbladder cancer

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Occupational and non-occupational risk factors in relation to an excess of primary liver cancer observed among residents of Brooklyn, New York

Article Abstract:

From 1976 to 1983, 632 deaths due to primary liver cancer (PLC) were recorded in Brooklyn, New York. This number exceeds the national average, so a study was conducted to examine the factors involved in this excess mortality. The high death rate affected both sexes and all racial groups. An examination of occupational factors revealed that household workers, non-domestic cleaning and food service workers, protective service workers, and transport equipment operators were all shown to have an increased risk of primary liver cancer. However, the distribution of occupations in Brooklyn in not significantly different from the rest of the nation, and it is unlikely that the excess of Brooklyn PLC deaths were due to occupational factors. It is worthy of note, however, that many of the occupations with high risk for PLC are also occupations which have a high mortality rate due to cirrhosis of the liver. In addition, Brooklyn residents have excess mortality due to cirrhosis as well as PLC. If cirrhosis, which in developed countries is generally a consequence of alcoholism, is, as some believe, a causative factor in primary liver cancer, the excess of PLC observed in Brooklyn may be accounted for. (Consumer Summary produced by Reliance Medical Information, Inc.)

Risk factors, Liver cirrhosis

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Childhood primary hepatocellular carcinoma

Article Abstract:

Primary hepatocellular carcinoma (PHC), a liver cancer, is sufficiently rare in children that only a few cases have been adequately described. In adults, PHC has been shown to be associated with hepatitis B virus, but this association had not been investigated in children with this cancer. In six cases observed over a seven-year period, hepatitis B antigen was discovered in four tumors. An additional child exhibited hepatitis B antigen in the blood serum, although viral antigen could not be directly observed in the tumor itself. Two mothers were also shown to be seropositive, raising the possibility that the virus was transmitted from mother to child. It is interesting to note that the patients observed ranged in age from 6 to 11 years, with a mean age of 8, a fact which is in marked contrast to the 20 years which is conventionally believed to be the incubation period of HPC in adults. The speed with which HPC develops in children may be an argument in favor of early immunization of children against hepatitis B virus. (Consumer Summary produced by Reliance Medical Information, Inc.)

Research, Cancer in children, Childhood cancer

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