Introduction: Dietary fat is an essential nutrient for human growth and development, but epidemiological studies have linked excess fat to the development of multiple malignancies. The few existing studies on ovarian cancer risk are inconsistent, possibly due to differences in sources and subtypes of fat. For example, omega-3 (n-3) polyunsaturated fatty acids (PUFAs) are thought to be antineoplastic, while omega-6 (n-6) PUFAs may promote carcinogenesis.

Approach: We evaluated dietary fat in relation to ovarian cancer risk in the prospective Shanghai Women’s Health Study (SWHS). Intake levels were determined from food frequency questionnaires (FFQ) administered at baseline and during follow-up; specific nutrient components were based on the sum of specific foods multiplied by nutrient content from the Chinese Food Composition Table. Cox proportional hazards regression was used to estimate relative risks (RR) and 95% confidence intervals (CI) for dietary fat and fatty acid components categorized into quintiles. Minimal models included age and residual adjustment for total energy intake; fully adjusted models also included education, years of menstruation, years of oral contraceptive use, parity, years of breastfeeding, family history of ovarian cancer, smoking, drinking, NSAID use, BMI, and physical activity.

Results: Among 73,144 SWHS participants, we identified a total of 219 ovarian cancer cases in 1,114,828 person-years of follow-up. We found significant dose-response relationships between increasing total PUFA (P-trend=0.032) and n-6 PUFA (P-trend=0.022) intakes and decreased ovarian cancer risk. In both minimally and fully adjusted models, women with the highest quintile of total dietary PUFAs were approximately 35% less likely to develop ovarian cancer (RR=0.65, 95% CI: 0.43-1.00), and women with the highest n-6 PUFA intake had a nearly 40% lower risk (RR=0.61, 95% CI: 0.40-0.93). Total fat, monounsaturated fat, and n-3 PUFA intake were not significantly related to ovarian cancer risk.

Conclusions: Findings from our preliminary analysis of a large prospective cohort of Chinese women suggest that total PUFA intake may be protective of ovarian cancer, and that this association may be driven by n-6 rather than n-3 PUFAs. Further evaluation, including stratification, sensitivity analysis, and evaluation of source of dietary fatty acids, is currently underway.

Citation Format: Eftitan Y. Akam, Harvey J. Murff, Yong-Bing Xiang, Nikhil K. Khankari, Hui Cai, Xiao O. Shu, Wei Zheng, Alicia Beeghly-Fadiel. Dietary fat, fatty acids, and ovarian cancer risk: Preliminary findings from the Shanghai Women’s Health Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3011. doi:10.1158/1538-7445.AM2017-3011