Calcitriol and Dexamethasone in Treating Patients With Prostate Cancer Who Have Undergone Surgery or Radiation Therapy

You may be eligible if

• DISEASE CHARACTERISTICS:
• Histologically confirmed adenocarcinoma of the prostate meeting all of the following criteria:
• * Curatively treated with radical prostatectomy OR definitive radiotherapy
• * No signs of clinical recurrence or dissemination of prostate cancer by digital rectal examination without tumor
• * No local recurrence by CT scan or MRI of the pelvis
• * No metastases by bone scan and chest x-ray NOTE: Prior Prostascint scans allowed regardless of results
• At least 3 prostate-specific antigen (PSA) measurements obtained over at least 90 days after radical prostatectomy on post-radiotherapy PSA nadir must be available
• * PSA at least 2 ng/mL after prostatectomy OR at least 4 ng/mL after prior radiotherapy
• * Patients previously treated with radiotherapy must have a PSA clearly rising from lowest value within 6 months after completion of therapy
• PATIENT CHARACTERISTICS:
• Age
• 18 and over
• Performance status
• ECOG 0-1
• Life expectancy
• At least 12 months
• Hematopoietic
• Platelet count at least 100,000/mm\^3
• Hemoglobin at least 10 g/dL
• Hepatic
• Bilirubin no greater than upper limit of normal (ULN)
• Alkaline phosphatase no greater than 2 times ULN
• Renal
• Creatinine less than 1.8 mg/dL
• Phosphorus normal
• No hypercalcemia (albumin-corrected calcium greater than ULN)
• No nephrolithiasis
• * Single episode of renal lithiasis allowed provided episode occurred more than 5 years prior to study
• Other
• Fertile patients must use effective double-barrier contraception for at least 1 week before, during, and for at least 2 weeks after study
• No symptomatic pancreatitis
• No uncontrolled diabetes
• No known or suspected inability to comply with study requirements (e.g., abuse of alcohol/drugs or psychotic states)
• Curatively treated condition associated with renal stones (e.g., hyperparathyroidism, bladder dysfunction, or obstructive uropathy) allowed provided patient has been free of stone formation for more than 5 years
• PRIOR CONCURRENT THERAPY:
• Biologic therapy
• Not specified
• Chemotherapy
• No prior chemotherapy for prostate cancer
• At least 24 months since prior chemotherapy for other diseases
• Endocrine therapy
• More than 6 months since prior hormonal therapy, including neoadjuvant or adjuvant androgen deprivation therapy (e.g., luteinizing hormone-releasing hormone analogue or antiandrogen)
• No prior androgen deprivation therapy of more than 8 months duration
• No prior hormonal therapy for prostate cancer more than 3 months after definitive local therapy
• No concurrent androgen therapy
• Radiotherapy
• See Disease Characteristics
• More than 3 months since prior radiotherapy for locally recurrent prostate cancer
• No concurrent radiotherapy, including for pain control
• Surgery
• See Disease Characteristics
• Other
• More than 4 weeks since prior investigational drugs
• No concurrent medication known to affect systemic calcium metabolism, including any of the following:
• * More than 400 IU of cholecalciferol supplements
• * More than 500 IU of vitamin A supplements
• * Calcium supplements
• * Fluoride
• * Antiepileptics