Dietary fat in relation to prognostic indicators in breast cancer.

The relation of diet, especially fat intake, to recognized prognostic indicators for breast cancer was investigated in 666 women with a newly diagnosed infiltrating breast carcinoma. Diet during the year preceding diagnosis was assessed by interview using a food frequency questionnaire covering the intake of 114 food items. Prognostic indicators included axillary node involvement at diagnosis, estrogen receptor status, and selected histologic features of the primary tumor such as nuclear grade, histologic grade, tubule formation, mitotic activity, and nuclear size of tumor cells. After adjustment for total energy intake, age, body weight, and tumor size at diagnosis, an increase in saturated fat intake was related to an increased frequency of node involvement at diagnosis among postmenopausal patients. In contrast, an elevation in polyunsaturated fat intake was related to a reduction of the percentage of patients with positive nodes at diagnosis. This relation was observed among both premenopausal and postmenopausal patients. Dietary fat was not related to the estrogen receptor status of tumors. No association was found between dietary habits and histologic features of the primary tumor. These data suggest that dietary fat may have an effect on the growth or spread of breast cancer during the preclinical phase of the disease and that this effect may vary according to the type of fat considered.