Alcohol, Postmenopausal Hormones, and Risk of Breast Cancer
Both alcohol and postmenopausal hormone use increase the risk for breast cancer. To determine whether alcohol interacts with hormone use to further increase this risk, researchers followed 5035 postmenopausal women who participated in the Copenhagen City Heart Study. Subjects reported alcohol intake and hormone use at baseline (1981–1983) and were followed in the Danish cancer registry until 2002. Of the participants, <0.1% were lost to follow up, and 267 developed breast cancer. Proportional hazard models were used to analyze associations between alcohol intake and breast cancer. The authors reported the following findings:
- Women who consumed alcohol versus nondrinkers (defined as consuming <1 drink per week in this study) had a small increase in breast cancer risk (hazard ratio [HR], 1.11 per drink/day; 95% CI: 0.99–1.25).
- Women who used hormones had a significantly increased risk of breast cancer (HR, 2.00 per drink/day) compared with women who did not use hormones.
- An interaction was shown between these two factors. Those women who had an intake of more than 2 drinks per day and took hormones had an increase in risk for breast cancer (HR, 4.74) compared with nondrinkers who did not use hormones.
- Alcohol was not associated with breast cancer among women who did not use hormones.
This study supports previous findings that postmenopausal hormone use modifies the risk of breast cancer associated with alcohol consumption. Further, alcohol consumption in this study was not associated with an increased risk of breast cancer among women who did not report hormone replacement therapy. This study did have a major limitation in that hormone and alcohol intake were measured only once during the 2-decade study. Nonetheless, these results and those of other studies suggest that women who drink moderately may reduce, or even avoid, an increase in the risk of breast cancer if they do not take hormones, do not have heavy drinking episodes, and have an adequate intake of dietary folate.R. Curtis Ellison, MD
Nielsen NR, Grønbaek M. Interactions between intakes of alcohol and postmenopausal hormones on risk of breast cancer. Int J Cancer. 2008;122(5):1109–1113.