Impact of Vitamin D Supplementation on the Rate of Pathologic Complete Response in Vitamin D Deficient Patients

Participants will receive standard of care neoadjuvant chemotherapy with doxorubicin (60 mg/m2) and cyclophosphamide (600 mg/m2) for 4 cycles and paclitaxel (80 mg/m2) weekly for 12 cycles. Doxorubicin and cyclophosphamide (AC) may be administered on a classical every 3 week or dose dense every 2-week (with growth factor support) schedule at the treating physician's discretion. Routine incorporation of carboplatin is not required, however use of carboplatin (AUC 1.5 to 2 weekly or AUC 6 on week 1, 4, 7, and 10) with paclitaxel is allowed at the treating investigator's discretion. Upon completion of neoadjuvant chemotherapy, all patients will undergo definitive surgery with either breast conservation or mastectomy with axillary lymph node staging. Type of surgery will be determined by the treating physician.

Participants with deficient levels of vitamin D will receive vitamin D supplementation at the initiation of chemotherapy with 50,000 IU of oral vitamin D3 (cholecalciferol) once a week to be continued for 20 weeks during neoadjuvant chemotherapy.

Participants that will receive Vitamin D will be asked to fill out a drug diary on a daily basis. Compliance and feasibility will be assessed through a drug diary and pill counts at set time points.