Fruit and vegetable intake and risk of breast cancer by hormone receptor status

Abstract

Background Estrogen receptor-negative (ER-) breast cancer has few known or modifiable risk factors. Because ER- tumors account for only 15% to 20% of breast cancers, large pooled analyses are necessary to evaluate precisely the suspected inverse association between fruit and vegetable intake and risk of ER- breast cancer. Methods Among 993 466 women followed for 11 to 20 years in 20 cohort studies, we documented 19 869 estrogen receptor positive (ER+) and 4821 ER- breast cancers. We calculated study-specific multivariable relative risks (RRs) and 95% confidence intervals (CIs) using Cox proportional hazards regression analyses and then combined them using a random-effects model. All statistical tests were two-sided. Results Total fruit and vegetable intake was statistically significantly inversely associated with risk of ER- breast cancer but not with risk of breast cancer overall or of ER+ tumors. The inverse association for ER- tumors was observed primarily for vegetable consumption. The pooled relative risks comparing the highest vs lowest quintile of total vegetable consumption were 0.82 (95% CI = 0.74 to 0.90) for ER - breast cancer and 1.04 (95% CI = 0.97 to 1.11) for ER+ breast cancer (Pcommon-effects by ER status