Change in alcohol consumption and all-cause mortality among postmenopausal women diagnosed with breast cancer

Evidence is inconsistent regarding an association between alcohol consumption and survival following a breast cancer diagnosis; therefore, we examined how change in alcohol consumption affects all-cause mortality (ACM) in a population of breast cancer survivors.

We prospectively assessed pre-diagnosis, pre- to post-diagnosis, and post-diagnosis change in alcohol consumption among 1,558 postmenopausal women (mean age-at-diagnosis: 71 years) diagnosed with non-metastatic invasive breast cancer from the American Cancer Society Cancer Prevention Study-II Nutrition Cohort (baseline: 1992-1993). Five categories of alcohol intake were determined at each assessment; change in alcohol consumption was categorized as stable, quit, reduced, and increased. Change occurred at a median of two years before (pre-diagnosis) and two years after (post-diagnosis) diagnosis. Cox proportional hazards regression was used to estimate adjusted hazard ratios (HR) and 95% confidence intervals (CI) for the associations between change groups and ACM.

Over a median follow-up of 12.6 years, 750 women died (130 breast cancer deaths). Compared to stable consumption, the association between cessation and ACM varied by change interval: pre-diagnosis (HR:0.91, CI:0.69-1.21), pre- to post-diagnosis: (HR:1.39, CI:1.12-1.73), post-diagnosis: (HR:0.98, CI:0.70-1.35). Alcohol reduction was not associated with ACM. Among women consuming ≥ 1 drink/day pre-diagnosis, increasing consumption elevated ACM risk (HR:1.83, 95%CI:1.02-3.31).

Alcohol reduction or cessation was not associated with a decrease in ACM among older breast cancer survivors. Among those drinking ≥ 1 drink/day, an increase in consumption pre-diagnosis was associated with higher mortality. Findings may be limited by uncontrolled confounding, a low prevalence of heavy drinking, or an insufficient duration of sustained change.