Vitamin D for Prostate Endocrine Therapy

PRIMARY OBJECTIVES: I. To evaluate the effect of high-dose vitamin D (HDVD) supplementation in prostate cancer patients on ADT-induced bone mineral density loss in the total hip over 52 weeks as measured by dual-energy x-ray absorptiometry (DXA). II. To evaluate the effect of HDVD supplementation in prostate cancer patients on ADT-induced bone mineral density loss in the femoral neck, distal radius, and lumbar spine (L1-L4) over 52 weeks as measured by DXA. SECONDARY OBJECTIVES: I. To evaluate the effect of HDVD supplementation on falls over 52 weeks as measured by the Falls History questionnaire. II. To evaluate the effect of HDVD supplementation on fractures over 52 weeks as determined by the Clinical Record Information - Follow-up Form. III. To evaluate the effect of HDVD supplementation on quality of life over 52 weeks as measured by the Functional Assessment of Cancer Therapy- Prostate (FACT-P). EXPLORATORY OBJECTIVE: I. To evaluate the effect of HDVD supplementation on pain, fatigue, sleep, and activities of daily living over 52 weeks as measured by patient-reported outcomes. OUTLINE: After undergoing collection of blood and DXA scan, patients are randomized to 1 of 2 arms. ARM I: Patients receive HDVD orally (PO) once a week (QW) for 52 weeks. Patients also undergo collection of blood and DXA scan on study. ARM II: Patients receive placebo PO QW for 52 weeks. Patients also undergo collection of blood and DXA scan on study.