Tree nut, peanut, and peanut butter intake and risk of postmenopausal breast cancer: The Netherlands Cohort Study

Purpose Nut intake has been associated with reduced mortality and risk of cardiovascular diseases, but there is only limited evidence on cancer. We investigated the relationship between nut intake and risk of postmenopausal breast cancer, and estrogen/progesterone receptor (ER/PR) subtypes. Methods In The Netherlands Cohort Study, 62,573 women aged 55-69 years provided information on dietary and lifestyle habits in 1986. After 20.3 years of follow-up, 2,321 incident breast cancer cases and 1,665 subcohort members were eligible for multivariate case-cohort analyses. Results Total nut intake was significantly inversely related to ER negative (ER -) breast cancer risk, with HR 0.55 (95% CI 0.33-0.93) for those consuming at least 10 g nuts/day versus non-consumers (p trend = 0.025). There were no significant inverse associations with ER + or total breast cancer. While there was no variation between PR subtypes, the ER-PR-subtype was also significantly inversely associated with nut intake, with HR 0.53 (95% CI 0.29-0.99), p trend = 0.037. Intake of peanuts and tree nuts separately was also inversely related to ER -breast cancer subtypes, while no associations were found with peanut butter intake. Conclusions Our findings suggest an inverse association between nut intake and ER -breast cancer, and no association with total or hormone receptor-positive subtypes.