Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed adenocarcinoma of the prostate

- Clinical stage T1b, T1c, or T2a disease

- Gleason score ≤ 6

- Maximal prostate-specific antigen (PSA) < 10 ng/mL

- Demonstrates intra-prostatic metabolite abnormalities, consistent with adenocarcinoma
of the prostate (i.e., ≥ 3 voxels with magnetic resonance spectroscopy imaging [MRSI]
scores 4-5) by baseline MRI and MRSI

- Has symptomatic benign prostatic hypertrophy and is currently undergoing watchful
waiting OR opting to undergo permanent seed implant (i.e., brachytherapy), but
requires neoadjuvant androgen suppression for prostate shrinkage

- No regional lymph node involvement

- No evidence of distant metastases

PATIENT CHARACTERISTICS:

- Zubrod performance status 0-1

- Able to swallow and retain oral medications

- No other prior or concurrent invasive cancer, other than localized basal cell or
squamous cell carcinoma of the skin

- No contraindications to MRI/MRSI, including any of the following:

- Prostate biopsy (within the past 8 weeks) and any continued post-biopsy bleeding

- Rectal bleeding

- Anal fissures

- Rectal surgery (end-to-end anastomosis)

- Inflammatory bowel disease

- Prior radical prostatectomy

- Hip replacement

- Certain types of penile implants

- Vascular clips

- Known anaphylactic reaction to latex compounds

- Anticoagulant drugs

- Severe claustrophobia

- Cardiac pacemaker

- Metal in eye

- Any other metallic or foreign object in the body

- No unstable serious co-morbidities including, but not limited to, myocardial
infarction, coronary artery syndrome, cardiac arrhythmias, symptomatic congestive
heart failure, or cerebrovascular accident

- No major medical or psychiatric illness that, in the investigator's opinion, would
preclude the completion of treatment and interfere with follow up

- No known hypersensitivity to any 5α-reductase inhibitor or drug chemically related to
the study drug

PRIOR CONCURRENT THERAPY:

- See Patient Characteristics

- No prior radical surgery (prostatectomy) or cryosurgery for prostate cancer

- No prior pelvic irradiation, prostate brachytherapy, or bilateral orchiectomy

- No prior or concurrent cytotoxic chemotherapy for prostate cancer

- No prior hormonal therapy, such as luteinizing hormone-releasing hormone agonists
(e.g., goserelin or leuprolide acetate), antiandrogens (e.g., flutamide or
bicalutamide), or estrogens (e.g., diethylstilbestrol)

- No prior or concurrent finasteride, dutasteride, other drugs with known
antiandrogenic properties (e.g., spironolactone or progestational agents), or any
dietary or herbal supplement (e.g., selenium, vitamin E, saw palmetto, or PC-SPES)