Alcohol Use and Breast Cancer Survival among Participants in the Women's Health Initiative

Alcohol increases the risk of breast cancer even at moderate levels of intake. However, the relationship between alcohol consumption and mortality among breast cancer patients is less clear. This study included women from the Women's Health Initiative observational study and randomized trial diagnosed with breast cancer (n = 7,835). Cox proportional hazards regression was used to estimate adjusted HRs and 95% confidence intervals (CI) for overall and breast cancer-specific (BCS) mortality associated with drinking alcohol before or after a breast cancer diagnosis. We also assessed whether changes in drinking habits after diagnosis are related to mortality. Women who were consuming alcohol prior to their breast cancer diagnosis had a nonstatistically significant 24% (95% CI, 0.56-1.04) reduced risk of BCS mortality and a 26% (95% CI, 0.61-0.89) reduced risk of all-cause mortality. Some variation was observed by estrogen receptor (ER) status as alcohol consumption was associated with a 49% (95% CI, 0.31-0.83) reduced risk of BCS mortality among ER(-) patients with no change in risk observed among ER(+) patients (HR = 0.97; 95% CI, 0.31-1.54), though the difference between these risks was not statistically significant (P for interaction = 0.39). Postdiagnosis alcohol consumption, and change in consumption patterns after diagnosis, did not appear to be associated with all-cause or BCS mortality. In this large study, consumption of alcohol before or after breast cancer diagnosis did not increase risks of overall or cause-specific mortality. Coupled with existing evidence, alcohol consumption is unlikely to have a substantial impact on mortality among breast cancer patients. Cancer Epidemiol Biomarkers Prev; 25(8); 1268-73. ©2016 AACR.