Treatment failure and dietary habits in women with breast cancer.

Abstract

Epidemiological and experimental evidence suggests that breast cancer risk can be reduced by dietary measures. Study of the relationships between dietary habits and prognosis in patients with breast cancer is essential to the design of diet intervention trials. Our purpose was to determine whether dietary habits are associated with disease-free survival in patients with breast cancer who have undergone treatment. We interviewed 240 women about their dietary histories. These women were 50-65 years old and had pathological stage I-II breast cancer with subsequent follow-up for 4 years; 209 of these women were postmenopausal. Differences in dietary variables between groups of patients were analyzed with bivariate and multivariate statistical methods. Cancers were classified as estrogen receptor (ER) rich (> or = 0.10 fmol/micrograms of DNA) in 149 patients and as ER poor (< 0.10 fmol/micrograms of DNA) in 71 patients. Fifty-two patients had treatment failure during follow-up. The 30 patients with ER-rich tumors who had treatment failure reported higher intakes of total fat, saturated fatty acids, and polyunsaturated fatty acids than did the 119 patients with ER-rich tumors who did not have treatment failure. The multiple-odds ratio (OR) for treatment failure in these women was 1.08 for each 1% increment in percentage of total energy (E%) from total fat. For treatment failure within the first 2 years, the OR was 1.19 for each 1-mg increase in vitamin E intake per 10 megajoules of energy. In women with treatment failure 2-4 years after diagnosis, ORs were 1.13 and 1.23 for each E% increment in total fat or saturated fatty acids, respectively. No association between dietary habits and treatment failure was found for women with ER-poor cancers. There was a tendency to a dose-response relationship (in quartiles) between intake of saturated fatty acids and disease-free survival, but the observed differences were not statistically significant. Dietary habits at the time of diagnosis may affect prognosis, at least for patients with ER-rich breast cancers. Dietary fat may have an effect on growth or spread of breast cancer, both of which may vary according to type of fat. Total fat and saturated fatty acids were the dietary parameters most strongly associated with risk for treatment failure. Dietary intervention might serve as an adjuvant treatment to improve breast cancer prognosis.