Vitamin D and Breast Cancer

Vitamin D metabolites may play a role in carcinogenesis. We analyzed 497 (case=152, control 1=179, control 2=166) archived samples of blood for two vitamin D metabolites: 25-hydroxyvitamin D (25-D) and 1,25-dihydroxyvitamin D (1,25-D). The samples were from black and white women participants in a previous case control study of breast cancer. Our data indicate that white women at the time of first diagnosis of breast cancer have significantly lower mean levels of 1,25-D than comparable women without breast cancer. In a comparison of white cases and control 1 subjects, the OR(95 percent CI) for lowest relative to highest quartile of 1,25-D was 5.2(2.1, 12.8), after adjustment for age, month of blood drawing, clinic, assay batch and sample storage time. The risk was significantly stronger in women above the age of 54, 4.7(2.1, 10.2) than in younger women 1.5(0.7, 3.0), X2(1df=4.7, p=O.03. We did not see the same pattern of risk associated with low 1,25-D among the small number of black women in the study. There were no differences between cases and controls in mean 25-D levels in either race. This work may have important implications for the chemoprevention and treatment of breast cancer.