Expression of 1,25-dihydroxy vitamin D3 receptor in breast carcinoma.

We investigated immunohistochemically the expression of 1,25 dihydroxy vitamin D3 receptors (VDRs) in normal human breast tissue and in breast carcinomas. For the first time, a VDR immunoreactivity score (VDR-IRS) in breast tissue is presented. Mean VDR-IRS in breast carcinomas was 7.28 compared to 1.55 in normal breast tissue. Comparing staining patterns for VDR and Ki-67, no visual correlation was found, indicating that VDR upregulation in breast carcinomas is not exclusively controlled by the proliferative activity of these tumor cells. Our study adds to the body of evidence that breast tissue may be a sensitive target organ for therapeutically applied new vitamin D analogues that exert few calcemic side effects.