Coffee Consumption and Invasive Breast Cancer Incidence among Postmenopausal Women in the Cancer Prevention Study II Nutrition Cohort

BACKGROUND There is limited evidence of a potential inverse association between coffee, particularly caffeinated coffee, consumption and postmenopausal breast cancer risk, and few studies have examined this association by tumor hormone receptor status. To provide further evidence, we examined total, caffeinated, and decaffeinated coffee consumption in relation to postmenopausal invasive breast cancer incidence overall, and by tumor estrogen receptor (ER) and/or progesterone receptor (PR) subtype. METHODS Among 57,075 postmenopausal women in the Cancer Prevention Study-II Nutrition Cohort who were cancer free and reported coffee intake in 1999, we identified 2,980 women diagnosed with invasive breast cancer during follow-up through June 2015. Multivariable-adjusted Cox proportional hazards regression was used to compute hazard ratios (HR) and 95% confidence intervals (CI). RESULTS Neither total, caffeinated, nor decaffeinated coffee consumption was associated with invasive breast cancer risk; HRs (95% CIs) comparing consumption of ≥2 cups per day with <1 cup per month were 0.99 (0.89-1.11), 0.96 (0.87-1.06), and 1.06 (0.95-1.19), respectively. Similarly, coffee consumption was not associated with risk of hormone receptor-positive (ER+ or PR+) or hormone receptor-negative (ER- and PR-) breast tumors. CONCLUSIONS These findings do not support an association between coffee consumption and invasive breast cancer risk among postmenopausal women. IMPACT This large prospective study contributes to the limited evidence on coffee consumption and breast cancer risk, finding no association overall or by tumor receptor subtype.