Calcitriol in Preventing Prostate Cancer in Patients With Prostatic Intraepithelial Neoplasia

DISEASE CHARACTERISTICS: Histologically confirmed high-grade prostatic intraepithelial neoplasia Diagnosed within the past 6 months No evidence of prostate cancer within the past 6 months No evidence of palpable nodules on digital rectal exam Prostate specific antigen ≤ 10 ng/mL within the past 3 months PATIENT CHARACTERISTICS: Age 18 and over Performance status ECOG 0-1 Life expectancy Not specified Hematopoietic Absolute neutrophil count ≥ 1,500/mm^3 Platelet count ≥ 100,000/mm^3 Hepatic SGOT and SGPT ≤ 1.5 times upper limit of normal Renal No uncontrolled renal failure No cancer-related hypercalcemia or kidney stones within the past 5 years Cardiovascular No uncontrolled coronary artery disease No uncontrolled congestive heart failure Other Prior malignancy allowed provided patient was curatively treated and has been disease-free for an appropriate time period for the specific cancer No known HIV positivity No active infection No major depression or suicidal ideation No other condition that would preclude study compliance No other uncontrolled medical condition PRIOR CONCURRENT THERAPY: Biologic therapy Not specified Chemotherapy No prior chemotherapy for any malignancy Endocrine therapy At least 2 weeks since prior and no concurrent finasteride (Prosear® or Propecia®) or other androgen suppressor No concurrent corticosteroids Radiotherapy Not specified Surgery Not specified Other At least 2 weeks since prior phenytoin or phenobarbital At least 2 weeks since prior ketoconazole No concurrent administration of any of the following: Magnesium-containing antacids Thiazide diuretics Calcium supplements Digoxin Herbal supplements Pharmacological doses of cholecalciferol (vitamin D) or its derivatives