DISEASE CHARACTERISTICS:

• Histologically confirmed adenocarcinoma of the prostate diagnosed within the past 180 days and at intermediate-risk for recurrence by meeting 1 or more of the following criteria:
  • Gleason score = 7
  • Prostate Specific Antigen (PSA) > 10 and ≤ 20 ng/mL
    • Baseline serum PSA value performed within 60 days with an FDA-approved assay (e.g., Abbott, Hybritech)
    • Baseline PSA must not be obtained during any of the following time frames:10-day period after prostate biopsy, after initiation of androgen-deprivation therapy, or within the past 30 days after discontinuation of finasteride (90 days for dutasteride)
  • Clinical stage T2b or T2c disease
  • Patients previously diagnosed with low-risk (Gleason score < 6, clinical stage < T2a, and PSA < 10 ng/mL) prostate cancer undergoing active surveillance who are re-biopsied and found to have intermediate-risk disease according to the protocol criteria are eligible for enrollment within 6 months of the repeat biopsy procedure
• Patients with Gleason Score ≥ 8, PSA > 20 ng/mL, OR clinical stage ≥ T3 are ineligible for this trial
  • If findings of extracapsular extension or seminal vesicle invasion are noted on prostate MRI, this study, if used, will not render patients ineligible for accrual to this protocol
  • Primary tumor staging for eligibility purposes is to be based on palpable or core biopsy evidence only with respect to extracapsular extension or seminal vesicle involvement
• No patients with all 3 intermediate-risk factors who also have ≥ 50% of the number of their biopsy cores positive for cancer
  • The percentage of biopsy cores involved will only be considered with respect to eligibility for those patients with all 3 of the above risk factors (i.e., patients with one or two of the above risk factors are eligible irrespective of the percentage of biopsy cores involved)
• Clinically negative lymph nodes as established by imaging (pelvic and/or abdominal CT scan or MRI), nodal sampling, or dissection within the past 60 days (required for patients with 2-3 risk factors)
  • Abdominal imaging not required for a single intermediate-risk factor (these studies may be obtained at the discretion of the treating physician)
  • Lymph nodes that are equivocal or questionable by imaging allowed without biopsy if nodes ≤ 1.5 cm
  • Any node > 1.5 cm on imaging requires a negative biopsy
• No evidence of bone metastases on bone scan within the past 60 days
  • Bone scan not required for patients with a single intermediate-risk factor (scan may be obtained at the discretion of the treating physician)
  • Equivocal bone scan findings allowed if plain film x-rays negative for metastasis

PATIENT CHARACTERISTICS:

• Zubrod performance status 0-1
• Absolute neutrophil count (ANC) ≥ 1,800/mm^3*
• Platelet count ≥ 100,000/mm^3*
• Hemoglobin ≥ 8.0 g/dL (transfusion or other intervention to achieve level allowed)*
  • NOTE: *For patients undergoing brachytherapy only.
• Fertile patients must use effective contraception during and for the 3 months after cessation of protocol treatment
• No invasive malignancy or hematological malignancy (e.g., leukemia, lymphoma, myeloma) within the past 5 years except adequately treated non-melanomatous skin cancer
  • Prior diagnoses of carcinoma in situ allowed
• No severe or active co-morbidity with any of the following:
  • Unstable angina and/or congestive heart failure requiring hospitalization within the past 6 months
  • Transmural myocardial infarction within the past 6 months
  • Acute bacterial or fungal infection requiring intravenous antibiotics
  • Chronic obstructive pulmonary disease exacerbation or other respiratory illness requiring hospitalization or precluding study therapy, within the past 30 days
  • Hepatic insufficiency resulting in clinical jaundice and/or coagulation defects
    • Laboratory tests for liver function and coagulation parameters not required for entry into this protocol
  • AIDS based upon current Centers for Disease Control (CDC) definition
    • HIV testing not required for entry into this protocol
    • HIV-seropositive patients who do not meet criteria for diagnosis of AIDS allowed

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• No prior radical surgery (prostatectomy), high-intensity focused ultrasound, or cryosurgery for prostate cancer
• No prior hormonal therapy, such as LHRH agonists (e.g., goserelin, leuprolide), antiandrogens (e.g., flutamide, bicalutamide), estrogens (e.g., DES), or bilateral orchiectomy
• No finasteride within past 30 days (90 days for dutasteride)
• No prior or concurrent cytotoxic chemotherapy for prostate cancer
  • Prior chemotherapy for a different cancer allowed
• No prior radiotherapy (RT), including brachytherapy, to the region of the study cancer that would result in overlap of RT fields
  • Patients undergoing brachytherapy must have transrectal ultrasound confirmation of prostate volume < 60 cc, American Urological Association (AUA) score ≤ 15 within the past 60 days of registration, and no history of prior transurethral resection of the prostate (TURP)
  • TURP allowed for patients who receive external-beam radiation therapy only