The association between 25-hydroxyvitamin D and mammographic density in healthy pre- and postmenopausal women regardless of the menstrual cycle phase: a cross-sectional study.

Vitamin D deficiency is a known risk factor of breast cancer. An association between vitamin D and breast density has been suggested; however, it remains controversial. The aim of this study was to determine the association between serum 25-hydroxyvitamin D [25(OH)D] level and mammographic density. Subjects in our study included 517 patients who visited the health promotion center of the University Hospital. Mammographic density was classified using the American College of Radiology, Breast Imaging Reporting and Data System. Analysis of variance was performed to clarify the association of serum 25(OH)D level and mammographic density, and odds ratio was calculated by ordinal logistic regression analysis. The mean serum 25(OH)D level was 14.3 ± 7.0 ng/mL in all subjects. In correlation analysis, weak negative correlation was observed between serum 25(OH)D level and mammographic density groups (r = -0.09, P = 0.049). However, ordinal logistic regression analysis showed no statistically significant association between serum 25(OH)D level and mammographic density (odds ratio: 0.75, 95% confidence interval: 0.50-1.13). Results of our study showed that there is no significant association between serum 25(OH)D level and mammographic density. It is thought to be an another mechanism of serum 25(OH)D level on breast cancer risk in addition to breast density.