Adult dietary fat intake and ovarian cancer risk.

The association of dietary fat intake with ovarian cancer risk has been inconsistent across populations. We examined dietary fat intake, overall and by type and ovarian cancer risk in two prospective cohort studies. We assessed long-term dietary fat intake among Nurses' Health Study (NHS) and NHSII participants using food frequency questionnaires administered every 2-4 years beginning in 1984 and 1991, respectively. We examined cumulative energy-adjusted intake of total fat, specific types of fat (animal, vegetable, saturated, monounsaturated, polyunsaturated and trans fat) and cholesterol. We identified 700 ovarian cancer cases in NHS and 196 in NHSII with dietary information. Cox proportional hazards regression was used to estimate associations between intake and ovarian cancer risk. Dietary fat intake changed over time in both cohorts and was lower in NHS than NHSII. Higher cumulative average intakes of animal fat and cholesterol were significantly positively associated with risk of ovarian cancer in NHS (relative risk [RR] comparing extreme quartiles = 1.57, 95% CI: 1.20, 2.06 and 1.35, 95% CI: 1.08, 1.69, respectively), but not in NHSII. Other dietary fat sources were not clearly associated with risk in either population. We did not observe clear associations between dietary fat and ovarian cancer risk in two large prospective cohort studies.