Abstract 4168: Alcohol consumption and risk of breast cancer in postmenopausal women: the NIH-AARP Diet and Health Study
Authors: Lew Jasmine Q , Park Yikyung , Freedman Neal , Hollenbeck Albert R. , Leitzmann Michael F , Brinton Louise A. , Hoover Robert N. , Schatzkin Arthur 
Published: May 2019

Abstract
Introduction: Epidemiologic studies have consistently shown an association between alcohol use and invasive postmenopausal breast cancer. Experimental data suggest that alcohol intake increases risk of breast cancer through its effect on estrogen, but observational studies of the association between alcohol use and breast cancer according to hormone receptor status have been sparse and inconsistent. In this context, we investigated if the relation between alcohol and breast cancer differed by hormone receptor status in postmenopausal women.
Methods: We analyzed 184,418 postmenopausal women (mean baseline age of 62 years) in the prospective NIH-AARP Diet and Health Study. At baseline, we assessed alcohol and other nutrient intakes with a food frequency questionnaire, and collected data on demographics, lifestyle, and medical history. We used Cox proportional hazards models to calculate relative risks (RR) and 95% confidence intervals (CI), adjusting for age, race, height, body mass index (BMI), physical activity, smoking history, parity, age at first birth, age at menopause, family history of breast cancer, frequency of breast biopsy, hormone replacement therapy (HRT) use, and intakes of fat, folate and energy.
Results: During an average of 7 years of follow-up, we identified 5,461 invasive breast cancer cases. 2,391 cases had hormone receptor status information: 1,641 ER+/PR+ cases, 366 ER-/PR-, 336 ER+/PR-, and 48 ER-/PR+ cases. 30.0% of women did not drink alcohol; the mean alcohol intake among drinkers was 8.2g/day (10th-90th percentile = 0.4-20.1 g/day). Alcohol was associated with increased risk of breast cancer: compared to no alcohol, the multivariate RR(95% CI) for &lt;5, 5-&lt;10, 10-&lt;20, 20-&lt;35, 35-&lt;45 and &gt;45g/day of intake, were 1.04 (0.98-1.11), 1.05 (0.93-1.17), 1.14 (1.03-1.26), 1.25 (1.09-1.42), 1.32 (1.00-1.74), 1.38 (1.17-1.62) ( p for trend&lt;0.001), respectively. ER+/PR+ tumor types showed a stronger association with alcohol than ER-/PR- tumor types: compared to no alcohol, the multivariate RR(95% CI) for &lt;1, 1-&lt;3, and ≥3 drinks/day, were, respectively, 1.07 (0.95-1.20), 1.32 (1.12-1.56), 1.51 (1.13-2.02) for ER+/PR+ tumors, 1.02 (0.80-1.30), 1.48 (1.05-2.08), 0.76 (0.35-1.66) for ER-/PR- tumors, and 1.11(0.86-1.44), 1.17 (0.80-1.71), 1.56 (0.85-2.89) for ER+/PR- tumors. The associations were similar for alcoholic beverage types. Compared to no intake, the multivariate RR (95% CI) for 1-&lt;3 and ≥3 drinks/day were 1.20 (0.99-1.55) and 1.73 (1.22-2.46) for beer; 1.20 (1.07-1.35) and 1.41 (0.87-2.28) for wine; and 1.27 (1.12-1.44) and 1.25 (1.04-1.51), respectively, for liquor. No significant alcohol-breast cancer interactions were observed with BMI, HRT use, family history of breast cancer, and folate intake.
Conclusion: Alcohol consumption, even at moderate levels, increased the risk of breast cancer. This positive association was largely confined to ER+/PR+ tumors.