A study of nearly 80,000 middle-aged women in the U.S. links smoking with an increased risk of breast cancer after menopause. The study also found an association between secondhand smoke and breast cancer among these postmenopausal women.
Compared with women who had never smoked, breast cancer risk was elevated by nine percent among former smokers and by 16 percent among current smokers. Breast cancer risk was significantly higher among chain smokers, as well as those who started smoking in their teenage years. An increased risk of breast cancer persisted for up to 20 years after smoking cessation.
Among women who had never smoked, those with the most extensive exposure to secondhand smoke (10 years or more during childhood, 20 years or more in adulthood at home, and 10 years or more in adulthood at work) had a 32 percent excess risk of breast cancer compared with those who had never been exposed to passive smoking.
1. 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. (open access)