Dietary Patterns and Risk of Ovarian Cancer in the California Teachers Study Cohort

Abstract

Previous studies have examined the association between individual foods or nutrients, but not overall diet, and ovarian cancer risk. To account for the clustering of foods in the diet, we investigated the association between dietary patterns and risk of ovarian cancer in the prospective California Teachers Study cohort. Of 97,292 eligible women who completed the baseline dietary assessment in 1995–1996, 311 women developed epithelial ovarian cancer on or before December 31, 2004. Based on principal components analysis, 5 major dietary patterns were identified and termed plant-based, high-protein/high-fat, high-carbohydrate, ethnic, and salad-and-wine. Multivariable Cox proportional hazards regression analysis was used to estimate associations between these dietary patterns and risk of incident ovarian cancer. Most of the dietary patterns were not significantly associated with ovarian cancer risk. However, women who followed a plant-based diet had higher risk; comparing those in the top quintile of plant-based food intake with those in the lowest quintile, the relative risk of ovarian cancer was 1.65 (95% confidence interval = 1.07–2.54; P _trend = 0.03). Associations with the 5 dietary patterns did not vary by known ovarian cancer risk factors or other behavioral or sociodemographic characteristics. Overall, our results show no convincing associations between dietary patterns and ovarian cancer risk.

ACKNOWLEDGMENTS

The authors would like to thank the CTS Steering Committee members who are responsible for the formation and maintenance of the cohort within which this study was conducted but who are not authors of this article: Hoda Anton-Culver, Rosemary Cress, Dennis Deapen, Susan Neuhausen, Rich Pinder, and Giske Ursin. This research was supported by Grants R03 CA113024 and R01 CA77398 from the National Cancer Institute; Contract 97–10500 from the California Breast Cancer Research fund; and the California Breast Cancer Act of 1993, California Department of Health Services. The funding sources did not contribute to the design or conduct of the study nor to the writing or submission of this article. The collection of cancer incidence data used in this study was supported by the California Department of Health Services as part of the statewide cancer reporting program mandated by California Health and Safety Code Section 103885; the National Cancer Institute's Surveillance, Epidemiology, and End Results Program under contract N01–PC–35136 awarded to the Northern California Cancer Center, Contract N01–PC–35139 awarded to the University of Southern California, and Contract N02-PC-15105 awarded to the Public Health Institute; and the Centers for Disease Control and Prevention's National Program of Cancer Registries under agreement #U55/CCR921930–02 awarded to the Public Health Institute. The ideas and opinions expressed herein are those of the authors and endorsement by the State of California, Department of Health Services, the National Cancer Institute, and the Centers for Disease Control and Prevention or their contractors and subcontractors is not intended nor should be inferred.

Notes

^a Food items with loading ≥ |0.30 | are shown.

^a Adjusted for race/ethnicity and total energy intake, with age as time scale and stratified by age at baseline.

^b Adjusted for race/ethnicity, total energy intake, parity, oral contraceptive use, lifetime strenuous physical activity, menopausal status/hormone therapy use, and wine intake, with age as time scale and stratified by age at baseline.

^c Pvalue for nonlinearity of trend > 0.05.

^d Continuous component score.