Abstract 643: Vitamin D deficiency increases breast cancer risk: A population based case-control study in the Chinese population

Vitamin D plays an important role in metabolism, cellular function and reproduction. Vitamin D has also been suggested to have potential protective effects against many cancers including breast cancer; however, the data from the epidemiological studies have been inconclusive. Our previous meta-analysis have found high dietary vitamin D intake significantly decreased breast cancer risk (RR = 0.91, 95% CI = 0.85-0.97) and women with higher circulating 25(OH)D level showed about 45% (95% CI = 0.38-0.80) decrease in breast cancer risk (Breast Cancer Res Treat. 2010;121(2):469-77). In a population-based case control study with 593 cases and 580 controls from Shanghai area, we have found that 80% of the normal women with severe vitamin D deficiency (less than 20ng/mL), 15.2% were of deficiency status (20 to 30ng/mL). Only 4.8% of women had sufficient vitamin D level (> 30ng/mL). However, in the breast cancer patients, nearly 96.1% were of vitamin D severe deficiency, 3.2% were of vitamin D deficiency and only 0.7% had sufficient levels. Based on a logistic regression analysis, compared to those with the lowest quintile of plasma 25(OH)D level, women with higher level had significant lower breast risk (Q2 vs. Q1, OR = 0.45, 95% CI = 0.33-0.63; Q3 vs. Q1, OR = 0.25, 95% CI = 0.17-0.36; Q4 vs.Q1, OR = 0.09, 95% CI = 0.06-0.15) showing a significant dose-effect relationship (p-trend < 0.001) after adjusted for the co-variants. We also found a seasonal distribution of vitamin D. Significantly lower vitamin D levels were found for the cases and controls in spring and summer (p < 0.01). In the controls the mean level of vitamin D was higher in the summer (17.76ng/ml) and autumn (16.25ng/ml), and lower in the spring (15.67ng/ml) and winter (10.75ng/ml). However, in the breast cancer patients, the plasma level of vitamin D was highest in the autumn (14.38ng/ml) and lowest in the spring (10.16ng/ml). These results provide a strong evidence that vitamin D may have a chemo-preventive effect against breast cancer. 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 643. doi:1538-7445.AM2012-643