Abstract A42: Intake of vitamins A, C, E, and folate and risk of ovarian cancer in a pooled analysis of 10 cohort studies
Authors: Koushik Anita , Smith-Warner Stephanie A. 
Published: May 2019

Vitamins A, C, E and folate have properties, such as modulation of DNA synthesis and repair, control of cellular differentiation and proliferation, as well as antioxidation, which are potentially cancer preventive. In a 2007 international panel review of the epidemiological literature published through 2006, the available data on the associations between intake of these vitamins and ovarian cancer risk were judged to be limited and inconclusive. Relatively few studies had been published and statistical power may have been limited in most studies. Among subsequent studies, sample sizes have been large in some though results remain inconsistent. In this project, we examined vitamin intakes from food only (dietary) and from food and supplements together (total) in relation to ovarian cancer risk by pooling the primary data from the following studies: Breast Cancer Detection Demonstration Project Follow-up Study, Canadian National Breast Screening Study, Cancer Prevention Study II Nutrition Cohort, Iowa Women's Health Study, Netherlands Cohort Study, New York State Cohort, New York University Women's Health Study, Nurses' Health Study, Nurses' Health Study II, and Swedish Mammography Cohort. Vitamin intakes were ascertained from a validated food frequency questionnaire administered at baseline in each study. Study-specific relative risks (RR) were estimated using the Cox proportional hazards model, and then combined using a random-effects model. Multivariate models included total energy intake and other potential ovarian cancer risk factors. Among 501,857 women, 1,973 cases of ovarian cancer occurred during a maximum follow-up of 7 to 22 years across studies. When analyzed as continuous variables the RRs for dietary and total intakes of each of the vitamins were not significantly associated with ovarian cancer. For increments of intake defined by the mean of the standard deviation of the mean intake across studies, the pooled multivariate RRs (95% CI) for total intake of each vitamin were 1.02 (0.97-1.07) for each 1300 mcg/day increase in vitamin A, 1.01 (0.99-1.04) for each 400 mg/day increase in vitamin C, 1.02 (0.97-1.06) for each 130 mg/day increase in vitamin E and 1.01 (0.96-1.07) for each 250 mcg/day increase in folate. When vitamin intakes were analyzed as categorical variables defined by study-specific quintiles of intake, the results were consistent with the continuous analyses and indicated no significant association. There was no evidence of statistically significant heterogeneity between studies in any of the analyses. Also, the pooled RRs did not vary greatly by levels of parity, oral contraceptive use, postmenopausal hormone use, smoking status or alcohol consumption, nor did associations greatly differ by histological type. We also examined use of specific vitamin supplements and multivitamins and did not observe a significant association with risk of ovarian cancer overall; the pooled multivariate RR (95% CI) for multivitamin use versus non-use was 1.00 (0.89-1.12). This large pooled analysis suggests that vitamins A, C, E and folate are not associated with the risk of ovarian cancer.

Citation Format: Anita Koushik, Stephanie A. Smith-Warner. Intake of vitamins A, C, E, and folate and risk of ovarian cancer in a pooled analysis of 10 cohort studies. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr A42.