Interstitial Brachytherapy With or Without External-Beam Radiation Therapy in Treating Patients With Prostate Cancer

RATIONALE: Radiation therapy uses high-energy x-rays and other sources to damage tumor cells. Interstitial brachytherapy uses radioactive material placed directly into or near a tumor to kill tumor cells. Combining interstitial brachytherapy with external-beam radiation therapy may kill more tumor cells. It is not yet known whether interstitial brachytherapy is more effective with or without external-beam radiation therapy in treating prostate cancer.

PURPOSE: Randomized phase III trial to compare the effectiveness of interstitial brachytherapy with or without external-beam radiation therapy in treating patients who have prostate cancer.

OBJECTIVES:

* Compare the 5-year freedom from progression in patients with intermediate-risk prostate cancer treated with interstitial brachytherapy with or without external beam radiotherapy (EBRT).
* Compare biochemical (i.e., prostate-specific antigen) failure, biochemical failure by the Phoenix definition, disease-specific survival, local progression, and distant metastases in patients treated with these regimens.
* Compare morbidity and quality of life of patients treated with these regimens.
* Determine the feasibility of collecting Medicare data in a large Radiation Therapy Oncology Group (RTOG) prostate cancer clinical trial for cost effectiveness and cost utility analysis of combined treatment with interstitial brachytherapy and EBRT.
* Prospectively collect diagnostic biopsy samples from these patients for future biomarker analyses.

OUTLINE: This is a randomized, multicenter study. Patients are stratified according to disease stage (T1c vs T2a or T2b), Gleason score (≤ 6 vs 7), prostate-specific antigen (\< 10 ng/mL vs 10-20 ng/mL), and prior neoadjuvant hormonal therapy (yes vs no). Patients are randomized to 1 of 2 treatment arms.

* Arm I: Patients undergo external beam radiotherapy 5 days a week for 5 weeks. Within 2-4 weeks of radiotherapy, patients undergo interstitial brachytherapy with iodine I 125 or palladium Pd 103 seeds.
* Arm II: Patients undergo interstitial brachytherapy only, as in arm I. Quality of life is assessed at baseline, at 4, 12, and 24 months, and then annually for 3 years.

After completion of study treatment, patients are followed at 3-5 weeks, at 4, 6, 9, and 12 months, every 6 months for 4 years, and then annually thereafter.

Eligibility Criteria:
DISEASE CHARACTERISTICS:

* Histologically confirmed adenocarcinoma of the prostate

  * T1c-T2b, N0, M0
* Intermediate-risk disease, as defined by 1 of the following:

  * Gleason score \< 7 AND prostate-specific antigen (PSA) 10-20 ng/mL
  * Gleason score 7 AND PSA \< 10 ng/mL
* No evidence of distant metastases
* Prostate volume ≤ 60 cc by transrectal ultrasonography
* American Urological Association voiding symptom score no greater than 15 (alpha blockers allowed)

PATIENT CHARACTERISTICS:

Age

* 18 and over

Performance status

* Zubrod 0-1

Life expectancy

* Not specified

Hematopoietic

* Not specified

Hepatic

* Not specified

Renal

* Not specified

Other

* Patients must use effective contraception
* No other malignancy within the past 5 years except basal cell or squamous cell skin cancer or carcinoma in situ at any other site
* No major medical or psychiatric illness that would preclude study therapy
* No hip prosthesis

PRIOR CONCURRENT THERAPY:

Biologic therapy

* Not specified

Chemotherapy

* No prior chemotherapy

Endocrine therapy

* Prior neoadjuvant hormonal therapy allowed provided the following are true:

  * Therapy was initiated within 2-6 months of study enrollment
  * Therapy was no more than 6 months in duration
  * Use of 5-alpha reductase inhibitors (e.g., finasteride) is discontinued before registration
* No concurrent hormonal therapy

Radiotherapy

* No prior pelvic radiotherapy

Surgery

* No prior radical surgery for prostate cancer
* No prior transurethral resection of the prostate
* No prior cryosurgery

Other

* No prior transurethral needle ablation of the prostate
* No prior transurethral microwave thermotherapy of the prostate