Alcohol consumption, smoking, and invasive breast cancer risk after ductal carcinoma in situ

Purpose Alcohol is an established risk factor for invasive breast cancer, and women with a prior ductal carcinoma in situ diagnosis are at higher risk of invasive breast cancer than the general population. However, for women with a prior ductal carcinoma in situ diagnosis, few studies have evaluated the association between alcohol and smoking and risk of subsequent invasive breast cancer. Methods Utilizing a population-based case–control design nested among women diagnosed with a ductal carcinoma in situ between 1995 and 2013, we compared 243 cases diagnosed with a subsequent invasive breast cancer and 423 individually matched controls never diagnosed with a subsequent breast cancer. Results Compared with never to occasional drinkers, drinkers consuming at least 7 alcoholic drinks per week on average at ductal carcinoma in situ diagnosis had a higher risk of invasive breast cancer that was borderline significant (OR 1.79, 95% CI 1.01–3.17, P value = 0.04). Smoking was not significantly associated with risk of developing an invasive breast cancer after adjustment for alcohol consumption. Conclusions These findings suggest that consuming at least one alcoholic drink per day on average is positively associated with invasive breast cancer for women with a prior ductal carcinoma in situ diagnosis. If confirmed, modulating alcohol consumption could be one strategy for women with a history of ductal carcinoma in situ to impact their risk of invasive breast cancer.