High Dose Vitamin D vs Standard Dose Vitamin D Study
High Dose Vitamin D vs Standard Dose Vitamin D Study
This study is being done to look at the difference, if there is a difference between two
 different doses of Vitamin D and the reduction of joint/muscle pain (arthralgia)that is
 caused by taking anti-estrogen medications (aromatase inhibitors) by breast cancer patients.
 The investigators hope to learn if taking a higher dose of Vitamin D is a good way to prevent
 aromatase inhibitor arthralgia (AIA).
Treatments with anti-estrogen agents for hormone receptor positive breast cancer is the most
 efficacious of systemic therapies, with aromatase inhibitors (AI's) being considered the most
 active anti-estrogen therapy in early stage breast cancer. But, use of these treatments has
 been shown to cause musculoskeletal (joint/muscle) side effects that sometimes cause patients
 to discontinue the use of them. Also, Vitamin D deficiency is a well know cause of a wide
 array of musculoskeletal issues. There is evidence that Vitamin D supplementation may help
 prevent arthralgia while on AI's. Therefore, the investigators want to see if giving a higher
 dose of Vitamin D could decrease the incidence of AIA as compared to a standard dose of
 Vitamin D. The investigators believe that this could possibly result in patients continued
 treatment with AI therapy for hormone receptor positive breast cancer.
Inclusion Criteria:

 -  All participants must be female and at least 21 years of age

 -  Signed informed consent

 -  Patients must have had histologically confirmed stage I-III breast carcinoma that is
 positive for Estrogen Receptor (ER) and/or Progesterone Receptor (PR).

 -  Post-menopausal

 -  Beginning adjuvant aromatase inhibitor therapy, with no previous use within the last 6
 weeks

 -  Bisphosphonates are allowed at the treating investigator¡¦s discretion

 -  Performance status (WHO/ECOG scale) 0-2.

 Exclusion Criteria:

 -  History of kidney stones

 -  Hypercalcemia at baseline, defined as any corrected calcium greater than the
 laboratory's normal parameters

 -  History of either symptomatic hypercalcemia or hyperparathyroidism, at the treating
 investigator's discretion

 -  Baseline Vitamin D level greater than 50 ng/mL

 -  Inability or unwillingness to comply with, or follow study procedures.

 -  Currently taking Phenytoin or phenobarbital -7 Currently taking cholestyramine or
 orlistat

 -  Malabsorption syndrome, such as Crohn's disease

 Prohibited Therapies: Patients may not take additional Calcium and Vitamin D aside from the
 study medications. Patients who are on cholestyramine or orlistat will not be allowed on
 the trial. Also, patients who are taking phenytoin or phenobarbital are not allowed on the
 trial either because of interaction between Vitamin D and anti-epileptic medications.