Food sources of fat and sex hormone receptor status of invasive breast tumors in women of the Malmö Diet and Cancer cohort.

We examined associations between food intakes and incident breast cancer, defined by estrogen receptor (ER) and progesterone receptor (PR) status in the Malmö Diet and Cancer cohort (∼17,000 women aged 45-73 yr). The hazard ratios (HRs) of ER+PR+ (n = 270), ER+PR- (n = 87), and ER-PR- (n = 61) tumors and all cancer (n = 544) were estimated after 10 yr of follow-up. In multivariate analysis of ER+PR+ tumors, a protective linear risk trend, indicating change between adjoining food categories, was seen with yogurt (HR = 0.89, 95% CI = 0.80-0.99), but increased risks with eggs (HR = 1.10, 95% CI = 1.01-1.20) and dried soups/sauces (HR = 1.10, 95% CI = 1.00-1.22). In ER-PR- tumors, vegetable-oil-based margarine (HR = 1.31, 95% CI = 1.09-1.59) and dried soups/sauces (HR = 1.31 95% CI = 1.05-1.64) showed increased risks. Heterogeneity was observed between ER+PR+ and ER-PR- tumors for vegetable-oil-based margarine (P < 0.01). Regular milk showed decreased, and dried soups/sauces increased, risk with all breast cancer. The study suggests that fat-containing food may contribute both to hormonal and nonhormonal mechanisms in breast tumor development and supports observations of positive associations between characteristics of Westernized diets and postmenopausal breast cancer.