Effects of High Dose Calcitriol in Breast Cancer Patients

Inclusion Criteria

• Must be female.
• Must have pathologically confirmed incident, primary invasive breast cancer.
• Must be awaiting surgical resection.
• Women of child-bearing potential (i.e. women who are pre-menopausal or not surgically sterile) must use acceptable contraceptive methods (abstinence, intrauterine device (IUD), or double barrier device) and must have a negative serum or urine pregnancy test within 1 week prior to beginning treatment on this trial. Contraceptive use needs to be continued at least 1 month after the trial has ended.
• Must provide informed consent.
• Must be willing to discontinue use of calcium and/or vitamin D supplements other than multivitamin supplementation.
• Participants must have an ionized serum calcium level within normal limits (1.19-1.29mmol/L) and a total corrected serum calcium of 10.2 mg/dl) or a history of hypercalcemia or vitamin D toxicity.
• Patients currently taking calcium supplements or aluminum-based antacids must immediately discontinue their use if they are to enroll in the study.
• Patients currently taking vitamin D supplements must immediately discontinue their use if they are to enroll in the study.
• Patients with a known sensitivity to calcitriol.
• Women who are pregnant or lactating.
• Women on antiresorptive drugs (e.g. bisphosphonates) within the past year.
• Women currently using oral contraception.
• Women with malabsorptive syndromes (i.e. cystic fibrosis, chronic pancreatitis) or taking medications that decrease the absorption of fat soluble vitamins (i.e. Orlistat, Questran).
• Participants assigned to calcitriol who are routinely taking a multivitamin supplement may continue the supplement as long as the amount of vitamin D in the supplement is not in excess of the RDA (recommended daily allowance) of 400 IU or 10 μg. If they are not taking a multivitamin supplement, they will be asked to not start supplementation while on study.