100 Cigarettes and Breast Cancer

Who's counting? Researchers from the Mayo Clinic looked at smoking history and other risk factors for breast cancer in 1,225 women who developed the disease and more than 6,800 who did not. They noted that earlier studies didn’t clearly define whether participating women were current or former smokers or had never smoked at all. For this study, the researchers defined "smokers" - current or former - as anyone who had cumulatively smoked more than 100 cigarettes at any time. They found that just over 10 percent of the women in their study were current smokers; almost 9 percent had quit smoking and 81 percent never smoked. Those who had smoked more than 100 cigarettes proved at substantially increased risk for breast cancer; but the study also demonstrated that quitting reduces this risk. The researchers also found that women who had used birth control pills for 11 years or longer had a 200 percent increased risk of breast cancer, that those who took post-menopausal hormone replacement therapy had an increased risk of 81 percent and that women who had had hysterectomies had a reduced risk of 35 percent. The study was published in the September/October, 2009 issue of The Breast Journal.