Serum vitamin D and breast density in breast cancer survivors.

BACKGROUND Vitamin D influences cellular proliferation and proliferation-related breast tissue characteristics, such as mammographic breast density. Little is known about vitamin D status, assessed by serum 25-hydroxyvitamin D [25(OH)D], and its relationship to breast density in breast cancer survivors. METHODS Participants were 426 postmenopausal breast cancer survivors from the Health, Eating, Activity, and Lifestyle Study. Women from New Mexico, Los Angeles, and western Washington were enrolled postdiagnosis. Data for this report are from an examination conducted 24 months postenrollment. Participants completed health-related questionnaires, gave fasting blood samples, and completed height and weight measurements. Serum [25(OH)D] was assayed by radioimmunoabsorbant assay. Breast dense area and percent density were measured from postdiagnosis-digitized mammograms. Multivariate linear regression tested associations of serum [25(OH)D] with mammographic breast density measures. RESULTS Of the 426 participants, 22.8% were African-American, 11.3% were Hispanic, and 62.8% were non-Hispanic white. We observed no associations of serum [25(OH)D] with either breast density or breast dense area. Among women with vitamin D deficiency (serum [25(OH)D], <16.0 ng/mL; n = 103), mean percent breast density was 8.0%, and among those with sufficient status (n = 99; serum [25(OH)D], > or = 32.0 ng/mL), mean percent density was 8.5%. Breast dense area averaged 27.2 and 26.2 cm2 for women with vitamin D deficiency and sufficiency, respectively. CONCLUSION Data from this multiethnic cohort of breast cancer survivors do not support the hypothesis that serum vitamin D, [25(OH)D], is associated with breast density in cancer survivors.