Fruit and Vegetable Intake and Risk of Breast Cancer by Hormone Receptor Status

Abstract

Estrogen receptornegative (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.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.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 < .001). Total fruit consumption was non-statistically significantly associated with risk of ER breast cancer (pooled multivariable RR comparing the highest vs lowest quintile 0.94, 95% CI 0.85 to 1.04).We observed no association between total fruit and vegetable intake and risk of overall breast cancer. However, vegetable consumption was inversely associated with risk of ER breast cancer in our large pooled analyses.