Background: Fat intake has been postulated to increase risk of ovarian cancer, but previous studies have reported inconsistent results.
Methods: The NIH-AARP Diet and Health Study, a large prospective cohort, assessed diet using a food frequency questionnaire at baseline in 1995-1996. During an average of 9 years of follow-up, 695 ovarian cancer cases were ascertained through the state cancer registry database. The relative risks (RRs) and 95% confidence interval (CI) were estimated using a Cox proportional hazard model.
Results: Women in the highest vs the lowest quintile of total fat intake had a 28% increased risk of ovarian cancer (RR(Q5 vs Q1)=1.28, 95% CI: 1.01-1.63). Fat intake from animal sources (RR(Q5 vs Q1)=1.30; 95% CI: 1.02-1.66), but not from plant sources, was positively associated with ovarian cancer risk. Saturated and monounsaturated fat intakes were not related to risk of ovarian cancer, but polyunsaturated fat intake showed a weak positive association. The association between total fat intake and ovarian cancer was stronger in women who were nulliparous or never used oral contraceptives.
Conclusion: Fat intake, especially from animal sources, was related to an increased risk of ovarian cancer. The association may be modified by parity and oral contraceptive use, which warrants further investigation.