DIETARY-FAT INTAKE AND RISK OF EPITHELIAL OVARIAN-CANCER

Background: Evidence exists that dietary fat may be a contributory fac tor in the development of hormone-related cancers such as ovarian canc er. Previous studies have demonstrated significantly higher circulatin g-estrogen levels among nonvegetarian women than among vegetarian wome n; the increase correlated directly with consumption of saturated fat, However, the contribution that dietary fat plays in the development o f hormone-related cancers remains unresolved. Purpose: Our purpose was to evaluate whether saturated fat intake increases the risk of ovaria n cancer development. Methods: Population-based sampling was used to a cquire cases and controls over a 3-year period from the study area, wh ich included the highly populated region surrounding the western end o f Lake Ontario, Canada. From the Ontario Cancer Registry, all histolog ically confirmed, primary malignant or borderline malignant epithelial ovarian tumors first diagnosed from November 1989 through October 199 2 among study-area residents aged 35-79 years were determined. In tota l, 631 eligible case subjects were identified, of whom 450 (71.3%) wer e interviewed concerning reproduction and diet; 564 randomly selected population control subjects were similarly interviewed. From the quant itative diet-history information, average daily intakes of macronutrie nts and micronutrients were calculated. Unconditional continuous logis tic regression methods were used for analysis, with adjustment for age at interview, number of full-term pregnancies, years of oral contrace ptive use, and total daily caloric intake. Results: Saturated fat cons umption was associated with increasing risk of ovarian cancer (odds ra tio [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 in take of unsaturated fats. Egg consumption also appeared related to inc reased 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 hav e resulted from disease-related changes in the dietary practices of ca se subjects prior to diagnosis. Consumption of vegetable fiber (but no t 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) remai ned statistically significant when included in the same regression mod el. Conclusion: Diet may contribute to risk of ovarian cancer developm ent. Implication: If confirmed in further studies, this association ma y allow women to appreciably lower their risk of ovarian cancer throug h dietary modifications: reducing the intake of saturated fats and eat ing more vegetables.