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

Background: 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. Methods: 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. Results: 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. Conclusion: In this large study, consumption of alcohol before or after breast cancer diagnosis did not increase risks of overall or cause-specific mortality. Impact: Coupled with existing evidence, alcohol consumption is unlikely to have a substantial impact on mortality among breast cancer patients. (C) 2016 AACR.