Dietary fat intake and risk of epithelial ovarian cancer.

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Evidence exists that dietary fat may be a contributory factor in the development of hormone-related cancers such as ovarian cancer. Previous studies have demonstrated significantly higher circulating-estrogen levels among nonvegetarian women than among vegetarian women; the increase correlated directly with consumption of saturated fat. However, the contribution that dietary fat plays in the development of hormone-related cancers remains unresolved. Our purpose was to evaluate whether saturated fat intake increases the risk of ovarian cancer development. Population-based sampling was used to acquire cases and controls over a 3-year period from the study area, which included the highly populated region surrounding the western end of Lake Ontario, Canada. From the Ontario Cancer Registry, all histologically confirmed, primary malignant or borderline malignant epithelial ovarian tumors first diagnosed from November 1989 through October 1992 among study-area residents aged 35-79 years were determined. In total, 631 eligible case subjects were identified, of whom 450 (71.3%) were interviewed concerning reproduction and diet; 564 randomly selected population control subjects were similarly interviewed. From the quantitative diet-history information, average daily intakes of macronutrients and micronutrients were calculated. Unconditional continuous logistic regression methods were used for analysis, with adjustment for age at interview, number of full-term pregnancies, years of oral contraceptive use, and total daily caloric intake. Saturated fat consumption was associated with increasing risk of ovarian cancer (odds ratio [OR] = 1.20 for each 10 g/day of intake; 95% confidence interval [CI] = 1.03-1.40; one-sided P = .0082). No relationship was seen with intake of unsaturated fats. Egg consumption also appeared related to increased risk (OR = 1.42 for each 100 mg of egg cholesterol per day; 95% CI = 1.18-1.72; two-sided P = .0002), though this association may have resulted from disease-related changes in the dietary practices of case subjects prior to diagnosis. Consumption of vegetable fiber (but not fruit or cereal fiber) was associated with decreased risk (OR = 0.63 for each 10 g/day; 95% CI = 0.49-0.80; two-sided P = .0001). All three nutrients (saturated fat, egg cholesterol, and vegetable fiber) remained statistically significant when included in the same regression model. Diet may contribute to risk of ovarian cancer development. If confirmed in further studies, this association may allow women to appreciably lower their risk of ovarian cancer through dietary modifications: reducing the intake of saturated fats and eating more vegetables.