MEMORANDUM FOR: Science Writers and Editors on the Journal Press List

Some Women May Be Genetically Susceptible to Cancer From Environmental Tobacco Smoke

November 23, 1999 (EMBARGOED FOR RELEASE 4 P.M. EST November 30)

Katherine Arnold, Deputy News Editor, Dan Eckstein, (301) 986-1891, ext. 112

New research suggests that some women may be genetically susceptible to lung cancer when exposed to the carcinogens in environmental tobacco smoke (ETS).

This finding is presented in the December 1 issue of the Journal of the National Cancer Institute by William Bennett, M.D., and Curtis Harris, M.D., National Cancer Institute, and colleagues.

The study involved white women in Missouri who had never smoked and who developed lung cancer. Missouri was chosen because of its stable population and its population-based cancer registry, and the study was confined to whites because of the small numbers of other racial/ethnic groups in the state.

Lung cancer tissue samples from which DNA could be extracted and analyzed were available for 106 women. These tissues were analyzed for the status of genes that have been associated with cancer and whose products activate or detoxify carcinogenic chemicals in tobacco smoke. Telephone and in-person interviews were used to obtain information about such lung cancer risk factors as age, ETS exposure, and consumption of vegetables and animal fat. ETS was defined in terms of "pack-years," with one pack-year being exposure within a confined space to smoke produced by a smoker consuming 20 cigarettes daily for a year.

The authors report that, when compared with women who had no exposure to ETS and who developed lung cancer, women exposed to ETS who developed lung cancer were 2.6 times more likely to have a specific genetic alteration in a cancer susceptibility gene known as GSTM1, which is responsible for inactivating carcinogens found in tobacco smoke. The excess risk of cancer for women with a defective GSTM1 gene rose with exposure to ETS, and women exposed to 55 pack-years of ETS were six times more likely to develop lung cancer.

The authors conclude that genetic susceptibility to tobacco smoke divides the population of never smokers into two roughly equal groups—one having a statistically significantly greater risk of lung cancer from ETS than the other.

In an editorial, Clarice Weinberg, Ph.D., and Dale Sandler, Ph.D., National Institute of Environmental Health Sciences, note that the Bennett et al. study involves only case patients, an approach that has both strengths and limitations. On the plus side, the editorial writers say, control subjects need not be sampled, saving money and obviating concerns about possible self-selection in any comparison group. However, some patients who classified themselves as never smokers may have been, in fact, active smokers. Also, the writers point out that there is the possibility that the case patients who could be genotyped were not representative of the whole series of case patients. Thus, Weinberg and Sandler conclude that many questions remain and the reported interaction between GSTM1 and ETS requires confirmation.

Contact: NCI Press Office, (301) 496-6641. (Note: The media contact is the NCI Press Office because the author is on the NCI staff.) Editorial: William Grigg, National Institute of Environmental Health Sciences, (301) 402-3378; fax (301) 496-0563.

Note: This memo to reporters is from the Journal staff and is not an official release of the National Cancer Institute (NCI) or Oxford University Press (OUP) nor does it reflect NCI or OUP policy. In addition, unless otherwise stated, all articles and items published in the Journal reflect the individual views of the authors and not necessarily the official points of view held by NCI, any other component of the U.S. government, OUP, or the organizations with which the authors are affiliated. Neither NCI nor any other component of the U.S. government nor OUP assumes any responsibility for the completeness of the articles or other items or the accuracy of the conclusions reached therein.



             
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