Vitamin D and Breast Cancer: Does Weight Make a Difference?

Inclusion Criteria:

   - Women who have undergone a core needle biopsy demonstrating an operable breast cancer
   whom have not yet had any further therapy.

   - No prior therapy for breast cancer.

   - Age 18 years or older.

   - Any menopausal status

   - Planned surgical resection of breast cancer or repeat core biopsy tissue sampling
   prior to initiation of neoadjuvant systemic chemotherapy.

   - Availability of tissue blocks from initial core needle biopsy.

   - Signed informed consent.

   - Willing to discontinue use of all supplements containing Vitamin D for the duration of
   the study, and take only the Vitamin D provided by the study.

Exclusion Criteria:

   - Presence of any Metastatic lesion.

   - History of parathyroid disease, hypercalcemia, or kidney stones.

   - History of Selective estrogen receptor modulator (SERM) or aromatase inhibitor
   therapy.

   - Receiving metformin.

   - History of renal failure requiring dialysis or kidney transplantation.

   - Women who are known to be pregnant or who are nursing. (As vitamin D does not have
   toxicity to the fetus, a negative pregnancy test is not a requirement to participate
   in the study.)

   - Patients planned for surgical therapy of their breast cancer or initiation of systemic
   chemotherapy, that would not allow for at least 7 days of vitamin D intervention

   - Any condition potentially interfering with subjects ability to comply with taking
   study medication.

   - Any medical condition that would potentially interfere with vitamin D absorption.

   - Current participation in another research study that would increase risk to subject,
   in the opinion of the investigators.

   - Patients currently taking more than 2000 IU of Vitamin D.