OBJECTIVE: It has been recently reported that expression of estrogen alpha (ER-alpha) and progesterone (PR) receptors in the normal mammary gland is inversely associated with breast cancer risk among postmenopausal women. We investigated whether dietary intakes are associated with the expression of ER-alpha and PR receptors in the apparently normal, as opposed to pathological, mammary tissue. METHODS: In a study in Greece, we examined associations of dietary intakes with ER-alpha and PR expression in the adjacent-to-pathological apparently normal mammary tissue of 562 women with either breast cancer (267 women) or BBD (299 women). Diet was assessed through an extensive food frequency questionnaire and results were analyzed using multiple logistic regression. RESULTS: Monounsaturated (p = 0.03) and, to a lesser extent, polyunsaturated lipids (p = 0.08) were positively associated with ER-alpha expression. Cereals and starchy roots were inversely associated with ER-alpha (p = 0.01), whereas milk and dairy products were inversely associated with PR expression (p = 0.02). Ethanol intake was non-significantly inversely associated with ER-alpha expression (p = 0.07). CONCLUSIONS: Our findings suggest that the weak associations of diet with breast cancer risk could be explained, to some extent, by effects of diet on receptor expression in the normal mammary gland.
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