Abstract 660: Dairy foods and nutrients in relation to risk of epithelial ovarian cancer

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL The identification of modifiable risk factors for ovarian cancer is important to reduce incidence and mortality. Previous studies have suggested that the lactose component of dairy foods may promote ovarian carcinogenesis via the accumulation of galactose (lactose metabolite) with potentially toxic effects on oocytes and disruption of ovarian/ pituitary feedback. Alternatively, high calcium levels in dairy products might decrease ovarian cancer risk by decreasing cell proliferation and increasing apoptosis by down-regulation of parathyroid hormone which has opposing effects. Our objective was to evaluate whether dairy foods and nutrients were associated with ovarian cancer risk in 1909 epithelial ovarian cancers and 1989 population based controls identified between 1992-2008 in the New England based case-control (NECC) study. At the time of enrollment, participants were interviewed in-person about known and suspected ovarian cancer risk factors and diet was assessed using a validated self-administered, semi-quantitative food frequency questionnaire. We used unconditional logistic regression to estimate associations between dairy exposures and ovarian cancer risk and polytomous logistic regression to test whether associations varied across histological subtypes of ovarian cancer or in cases that were classified as rapidly fatal vs. less aggressive cases. Multivariate models were adjusted for study center/phase, age, number of pregnancies, oral contraceptive use, tubal ligation, family history of ovarian cancer and total calories. We observed a significantly decreased risk of ovarian cancer with higher intakes of dietary and total (diet + supplements) calcium (dietary calcium: Quartile 4 (Q4) vs. Q1 OR= 0.74 (95% confidence interval (CI) = 0.62 - 0.89); total calcium: Q4 vs. Q1 OR = 0.61 (95% CI = 0.50 - 0.74)), Ptrend < 0.001 in both comparisons. Higher intakes of dietary and total vitamin D also were associated with a modest but statistically significant decreased risk of ovarian cancer (dietary vit D: Q4 vs. Q1 OR=0.82 (95% CI = 0.68 - 0.99); total vit D: Q4 vs. Q1 OR = 0.76 (95% CI = 0.63 - 0.92), Ptrend= 0.03 and 0.01 for dietary and total vitamin D, respectively. In models that were mutually adjusted for total calcium, total vitamin D and lactose, the association with calcium retained significance while the association with vitamin D was no longer significant. We did not observe an association between lactose and ovarian cancer risk and we observed similar associations for calcium, vitamin D and lactose among case groups defined as rapidly fatal or less aggressive. Together these results confirm previous reports that calcium appears to be protective for ovarian cancer. Prior studies of vitamin D and ovarian cancer risk have been inconsistent, however we observed a modest protective association that warrants further consideration. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 660. doi:1538-7445.AM2012-660