A new US-based observational study has shown that alcohol intake before and after a breast cancer diagnosis is not associated with disease-specific survival. Furthermore, moderate alcohol consumption might benefit cardiovascular outcomes and overall survival.

Previously, alcohol consumption has been shown to increase the risk of developing breast cancer. However, whether this modifiable life-style choice affects survival after diagnosis has been unclear. This new study assessed 22,890 women with breast cancer, and included a median follow up of 11.3 years. All women reported their prediagnostic alcohol consumption, and a subset of 4,881 women reported their postdiagnostic drinking habits.

More than 80% of the women reported drinking at least one drink per week before their diagnosis, with 50% of the total cohort consuming 1–2 drinks per week. After adjusting for first-degree family history, age at the birth of first child, menopausal status, BMI and smoking status—amongst other correlates—moderate prediagnostic alcohol consumption (3–6 drinks per week) was found to be associated with improved survival compared with nondrinkers, but heavy consumption (≥10 drinks per week) was not associated with improved cancer-specific survival.

Credit: Up the Resolution

In the subset included for postdiagnosis analysis, 23% of women reported abstaining from drinking alcohol. However, abstaining did not seem to affect their outcomes; disease-specific survival was similar in drinkers and nondrinkers. In fact, nondrinkers were more likely than women who consumed alcohol to die from cardiovascular disease, which is a known mortality cause among breast cancer survivors.

The precise relationship between alcohol and cancer risk is unclear. As alcohol is thought to increase endogenous oestrogens, women with hormone-receptor-positive cancers might be expected to respond favourably to abstaining from alcohol after diagnosis. However, further research is needed to ascertain the true risks.