According to two recent articles published in The Lancet and the
American Journal of Epidemiology, smoking at a young age appears to significantly increase the risk of developing breast cancer in women.
Breast cancer claims the lives of approximately 40,000 women each year in the United States alone. Since this disease occurs so frequently, researchers are evaluating both genetic and environmental factors in an attempt to determine if associations exist between specific variables and the development of breast cancer. One variable that is being studied is smoking.
One clinical study, as published in the American Journal of Epidemiology, involved nearly 470 women who had been diagnosed with premenopausal breast cancer. Data was collected regarding lifetime active and passive smoking among these women and was compared to over 1,000 women of approximately the same age who had not been diagnosed with breast cancer. Compared with women who had never actively smoked or been consistently exposed to passive smoke, former smokers had a 20% increased risk of developing premenopausal breast cancer and current smokers had a 50% increased risk of developing premenopausal breast cancer. The risk of developing breast cancer increased the longer a woman had smoked and decreased the longer it had been since she quit smoking. Women who had the highest exposure to active and passive smoking had an 80% increased risk of developing premenopausal breast cancer
1.A second clinical study, as published in
The Lancet, involved over 700 women under the age of 75 years who had been diagnosed with breast cancer. The researchers assessed data regarding all known or suspected risk factors, smoking and alcohol consumption and compared these risk factors to a group of over 1,000 women who did not have breast cancer. Of the 318 premenopausal women with breast cancer, there was nearly a 70% increase in the incidence of breast cancer if women had been pregnant and started smoking within 5 years from the initiation of menstruation, or if women had not had children but smoked 20 or more cigarettes daily or had a 20-pack year history. Conversely, in the 700 postmenopausal women with breast cancer, their risk was significantly reduced if they had gained weight since the age of 18 and had started smoking after a first fullterm pregnancy. Researchers speculate that this reduction in breast cancer is due to the interference of smoking with female hormones
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2.Both of these studies indicate that smoking increases the risk of developing premenopausal breast cancer in women. This provides further reason to discourage teenagers from starting to smoke. Women who started smoking early may wish to discuss their risks of developing breast cancer and appropriate screening measures with their physician. Further studies will be conducted to verify these findings, particularly those in postmenopausal women.
1.Kropp S, Chang-Claude J. Active and passive smoking and risk of breast cancer by age 50 years among German women.
American Journal of Epidemiology. 2002;156:616-626.
2.Band P, Le N, Fang R, Deschamps M. Carcinogenic and endocrine disrupting effects of cigarette smoke and risk of breast cancer.
The Lancet. 2002;360:1044-1049.
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