Alcohol use and breast cancer survival among participants in the Women's Health Initiative

Abstract

 
 May 19, 2016

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 WHI observational study and randomized trial diagnosed with breast cancer (n=7,835). Cox proportional hazards regression was used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for overall and breast-cancer-specific 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 non-statistically significant 24% (95% CI: 0.56-1.04) reduced risk of breast-cancer-specific (BCS) mortality and a 26% (95% CI: 0.61-0.89) reduced risk of all-cause mortality. Some variation was observed by 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). Post-diagnosis 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.