A team of researchers has shown that a certain type of chemoprevention used to experimentally deter liver cancer from developing is effective. The researchers gave the drug oltipraz, originally developed to treat schistosomiasis, to a group of people at high risk for developing liver cancer. The oltipraz changed the way in which the study group metabolized aflatoxin, a liver carcinogen produced by a fungus that contaminates foods like corn and peanuts.

They were able to show that the oltipraz induced phase 2 enzymes which altered the disposition of aflatoxin in the study group. This was the first time that the mechanism by which this chemopreventive agent worked was identified and confirmed with human subjects. The study establishes proof of principle that chemo-preventive agents can work by changing the disposition of environmental carcinogens. It appears in the February 17, 1999 issue of the Journal of the National Cancer Institute.

Liver cancer is a major cause of cancer deaths worldwide and claims approximately 400,000 lives in China each year. It is one of the fastest growing cancers in the United States and is also a problem in Canada which has large numbers of Chinese immigrants. Two of the major risk factors for liver cancer in China are infection with hepatitis B and aflatoxin in the diet. Aflatoxins are produced by some strains of the Aspergillus fungi and are found in much of the food supply in certain parts of China. They are commonly found in corn, peanuts, soya sauce, and fermented soy beans.

 Senior author Thomas Kensler, PhD, professor, Environmental Health Sciences, said, "We know a lot about how aflatoxin works. We were able to develop the analytic tools to measure aflatoxin elimination, and that enabled us to see if oltipraz made a difference in that process." Lead author Jia-Sheng Wang MD, PhD, research associate, Environmental Health Sciences
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Contact: Kathy Moore
kwojciec@jhsph.edu
410-955-7619
Johns Hopkins University Bloomberg School of Public Health
17-Feb-1999