Alcohol Intake and Risk of Breast Cancer by Histologic Subtype and Estrogen Receptor Status Among Women Aged 55 to 74 Years.

Previous studies suggest that alcohol consumption and risk of breast cancer may differ by histologic subtype and hormone receptor status, though results are not entirely consistent. In this population-based case-control study, we evaluated the association between alcohol consumption and risk of invasive ductal carcinoma (IDC), invasive lobular carcinoma (ILC), and invasive ductal-lobular carcinoma (IDLC) overall and by estrogen receptor (ER) status, among women aged 55-74 years of age. Using polytomous regression, associations between current alcohol consumption, overall and by type of alcohol, and breast cancer risk were evaluated in 891 controls and 905 IDC, 567 ILC, and 489 IDLC cases. Current alcohol use was moderately associated with risk of ILC (odds ratio = 1.25, 95% confidence interval 0.99, 1.58) with a positive dose-response relationship based on average number of drinks per week consumed (P  = 0.0005). When further stratified by ER status, alcohol use was positively associated with risk of ER+ ILC (P = 0.002) and ER+ IDC (P = 0.02), but inversely associated with risk of ER-IDC (P = 0.01). No association between alcohol and risk of IDLC tumors was observed. While the link between alcohol consumption and breast cancer risk is well established, our results suggest that the increased risk associated with alcohol is largely limited to ER+ ILC and ER+ IDC. Thus, avoiding or moderating alcohol consumption may be one way that women can lower their risks of these forms of breast cancer.