Influence of estrogen receptor status on dietary risk factors for breast cancer.

It has been suggested that the relation between diet and breast cancer may depend on estrogen receptor (ER) status. We examined the responses to a self-administered questionnaire on frequency of consumption of various foods by 493 women with breast cancer (160 with ER-negative tumours and 333 with ER-positive tumours) and 527 controls whose menopausal status was known. Analysis of the reported consumption of foods selected for their fat or carotene content showed no clear distinction in dietary factors between the ER-negative and ER-positive groups. Frequent consumption of meat fats generally increased the risk of both ER-negative and ER-positive tumours; there were no clear trends in risk associated with vegetable consumption for either ER group. Fish was the only item affecting the risk for ER-negative and ER-positive tumours differently, frequent consumption reducing the risk for the former (p = 0.02). The results do not support the hypothesis that ER status influences the relation between dietary fat consumption and risk of breast cancer.