The following major review article will appear June 2 in the Web edition of Chemical Research in Toxicology, a peer-reviewed journal published by the American Chemical Society, the world's largest scientific society.
First comprehensive review in a decade provides new insights on mechanisms of cancer induction by nitrosamines in tobacco products
A series of chemical compounds--known as nitrosamines--found in unburned tobacco and tobacco smoke have been strongly linked to lung cancer formation, says Stephen S. Hecht, Ph.D., of the University of Minnesota Cancer Center in Minneapolis. In the first comprehensive review in over a decade, Hecht summarizes all the peer-reviewed studies of the biochemistry, biology, and carcinogenicity of these tobacco- specific nitrosamines.
The tobacco specificity of these carcinogens is important, Hecht says, because they provide a link between nicotine addiction and cancer that can be attributed only to tobacco. This is in contrast to other smoke carcinogens such as polyaromatic hydrocarbons, which occur in the diet and the general environment. Other than nicotine chewing gum, Hecht says that there is no published evidence that these tobacco-specific nitrosamines are found in any other products except tobacco products. For example, the detection of a nitrosamine metabolite in the urine of non-smokers exposed to environmental tobacco smoke specifically implicates tobacco as the source of this carcinogenic exposure, according to Hecht. He maintains that this finding strengthens the argument that passive smoking causes lung cancer.
By developing the ways in which cancer is formed by cancer-specific nitrosamines in animal models, their fate in humans can be more fully determined, Hecht believes. This is the focus of his own research, to elucidate the factors which influence cancer development upon exposure to carcinogens.
Hecht also suggests that by understanding the way cancer is induced by tobacco-specific nitrosamines, more effective approaches toward prevention of tobacco-related cancers can be designed. Because lung cancer therapy is still largely unsuccessful, the use of chemical agents to inhibit the carcinogenicity of tobacco smoke--called chemoprevention--remains as a viable way to prevent cancer death in addicted smokers and ex-smokers, Hecht adds. Many agents have been tested in mice, and phase I clinical trials for the leading candidate, an isothiocyanate called PEITC, are being initiated.
Researcher contact: Dr. Stephen S. Hecht,
612-624-7604 (phone); 612-626-5135
(fax);
hecht002@gold.tc.umn.edu (email);
or Coleen Southwell,
Director of
Communications, University of Minnesota Cancer Center
612-626- 1107;
south011@tc.umn.edu
For a copy of an earlier release on Dr. Hecht's research on nitrosamines and environmental tobacco smoke, or a copy of this 45-page review, call Sally Pecor at 202-872-4451.
Journal
Chemical Research in Toxicology