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