The Association of Low-To-Moderate Alcohol Consumption with Breast Cancer Subtypes Defined by Hormone Receptor Status.

BACKGROUND Alcohol is a well-established risk factor for breast cancer, but pathways involved in alcohol-related breast carcinogenesis are not clearly defined. We examined the association between low-to-moderate alcohol intake and breast cancer subtypes by tumor hormone receptor status. MATERIALS AND METHODS A hospital-based case-control study was performed in 585 cases and 1,170 controls. Information on alcohol intake and other risk factors was collected via a questionnaire. Logistic regression was used for analyses. All statistical tests were two-sided. RESULTS The odds ratio of breast cancer was 1.75 (95% confidence interval [CI]: 1.21-2.53) in women who consumed ≤5 drinks/week, and 3.13 (95% CI: 1.81-5.43) in women who consumed >5 drinks/week, both compared with non-drinkers for ≥10 years, after adjustment for age and other confounders. The association of alcohol intake with estrogen receptor-positive breast cancer was stronger than with estrogen receptor-negative: the odds ratio per 1 category increase was 2.05 (95% CI: 1.49-2.82) and 1.29 (95% CI: 0.85-1.94) (P-heterogeneity = 0.07). There was no evidence of an interaction between alcohol intake and menopausal status (P = 0.19) in overall group; however, it was significant in estrogen receptor-positive breast cancer (P = 0.04). CONCLUSIONS Low-to-moderate alcohol intake is associated with the risk of estrogen receptor-positive breast cancer with the strongest association in postmenopausal women. Since alcohol intake is a modifiable risk factor of breast cancer, every woman should be informed and advised to control alcohol use.