Effect of High Dose Vitamin D on Cancer Biomarkers and Breast Cancer Tumors

This is a phase I/II open-label, non-randomized study. In phase I, a fixed weekly course of oral high-dose Vitamin D (VD) is planned for either 3, 4 or 5 weeks; patients will be sequentially enrolled into 3 groups (A, B or C respectively) in a manner such that no more than two patients may have treatment-limiting toxicities (TLTs). After the group with the optimal duration of VD therapy to achieve a "favorable response" is determined, phase II will begin enrollment. Patients must be scheduled to have surgery performed within 2- weeks of the last dose of VD.