Effects of High Dose Calcitriol in Breast Cancer Patients

The calcitriol intervention is aimed at reducing fracture risk by maintaining proper bone
density. Calcitriol is efficacious in maintaining proper bone health and muscle mass among
the general population, but little research has been done on breast cancer patients. In
addition, calcitriol may be effective in reducing tumor proliferation and angiogenesis, while
increasing tumor apoptosis. Each of those factors could have beneficial effects on breast
cancer outcomes.

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 < 10.2mg/dl.

Exclusion Criteria:

- Subjects with life-threatening conditions that would preclude them from breast cancer
treatment including: chronic cardiac failure, which is unstable despite medication
use; uncontrolled hypertension; uncontrolled diabetes mellitus; or unstable coronary
artery disease.

- Patients with severe metabolic disorders, which includes phenylketonuria (PKU),
homocystinuria, and Fabry's disease, that would preclude them from taking calcitriol.

- Patients with a previous history of any other cancer except non-melanomous skin cancer
within the past 5 years.

- Patients with impaired renal function (CRCL < 60 mL/min) or who had kidney stones
(calcium salt) within the past 5 years.

- Patients with hypercalcemia (corrected serum CA > 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.