Postmenopausal women who smoke cigarettes have up to a 16 percent higher risk of developing breast cancer compared to women who have never smoked, according to an open access 10-year study published in March 2011 in BMJ.com. In addition, the risk of developing breast cancer was elevated by nine percent among women who used to smoke.
The study also finds that postmenopausal women who were exposed extensively to secondhand smoke, either in childhood or as adults, may have a more than 30 percent excess risk of developing breast cancer.
"Our findings highlight the need for interventions to prevent initiation of smoking, especially at an early age, and to encourage smoking cessation at all ages," the study's lead researcher concludes.
Women’s Health Initiative Observational Study
Almost 80,000 women, age 50-79 years, across 40 clinical centers in the United States, participated in this study. The women were part of the Women’s Health Initiative Observational Study, which was designed to address major causes of morbidity and mortality in postmenopausal women. More than 3,200 cases of invasive breast cancer were identified by the researchers during 10 years of follow-up.
Link Between Tobacco Smoking and Breast Cancer
The results show that smokers have a 16 percent increased risk of breast cancer after menopause. The increased risk for former smokers is nine percent. The highest breast cancer risk was among women who had smoked cigarettes for more than 50 years or more compared with women who had never smoked. Women who started smoking cigarettes as teenagers were also at particularly high risk. An increased risk of breast cancer continued for up to 20 years after quitting smoking.
Secondhand Smoke and Risk of Breast Cancer
The study findings also reveal that among non-smoking women, those who had been exposed to secondhand smoke for more than 10 years in childhood, over 20 years as an adult at home and over 10 years as an adult at work, had a 32 percent excess risk of breast cancer.
The researchers emphasize, however, that their analysis of the link between breast cancer and secondhand smoke was restricted to the most extensive passive smoking category and therefore more research is needed to confirm these findings.
Reference:
Luo J, Margolis KL, Wactawski-Wende J, et al. Association of active and passive smoking with risk of breast cancer among postmenopausal women: a prospective cohort study. BMJ 2011; 342: d1016. Boffetta P, Autier P. Is breast cancer associated with tobacco smoking? BMJ 2011; 342: d1093.
Juan Ramos - Juan Ramos is a health communication specialist based in Boston, Massachusetts, USA. He has worked in the non-profit sector for more than ...
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