Selenium in Preventing Prostate Cancer

DISEASE CHARACTERISTICS: * Clinical indicators consistent with the community standards of medical care that would justify a biopsy of the prostate for the diagnosis of cancer, including ≥ 1 of the following: * PSA level above the absolute value of 4 ng/mL or above a published age-ethnic adjusted PSA level appropriate for the community * Rising PSA that should represent a clinically significant PSA velocity (e.g., an estimated annual change in the PSA velocity ≥ 0.75 ng/mL) * Abnormal digital rectal examination of the prostate that identifies a clinically significant change in the prostate (e.g., a prostate nodule or a change in the firmness of the prostate) * Documentation of the clinical assessment that justified the prostate biopsy that allows classification of the patient to high-risk groups * Prostate biopsy negative for cancer within the past 12 months * Prostate biopsy negative for high-grade prostatic intraepithelial neoplasia (PIN) * PIN allowed provided it is grade 1 PATIENT CHARACTERISTICS: * Creatinine \< 2 times upper limit of normal (ULN) * Bilirubin \< 2 times ULN * SGOT and SGPT \< 2 times ULN * Alkaline phosphatase \< 2 times ULN * No history of a prior malignancy except for the following: * Adequately treated basal cell or squamous cell carcinoma * Adequately treated (i.e., complete surgical removal with negative margins) stage I cancer from which the patient is currently in complete remission * Any other cancer from which the patient has been disease-free for 5 years PRIOR CONCURRENT THERAPY: * See Disease Characteristics * No prior systemic chemotherapy or radiotherapy * At least 90 days since prior and no other concurrent selenium \> 55 μg/day as a dietary supplement (including multivitamin supplements) * More than 30 days since prior and no concurrent participation in any other clinical trial involving a medical, surgical, nutritional, or life-style intervention (e.g., dietary modifications, exercise)