High-dose-rate interstitial brachytherapy as a monotherapy for localized prostate cancer: Treatment description and preliminary results of a phase I/II clinical trial

Purpose: To improve results for localized prostate cancer, a prospective cl inical trial of hyperfractionated Iridium-192 high-dose-rate (HDR) brachyth erapy as a monotherapy was initiated. Methods and Materials: Between May 1995 and September 1998, 22 implants wer e performed on 22 patients with localized prostate cancer (T1:T2:T3:T4 = 4: 6:9:3) at Osaka University Hospital. Nineteen patients, who had T3-T4 tumor s or pretreatment PSA greater than or equal to 20.0 ng/mL, received hormone therapy. No patient had external beam radiation. Transperineal needle impl ants using real-time ultrasound guidance were performed, followed by dose o ptimization program. Patients were irradiated twice a day, with a time inte rval of more than 6 h. Total dose was 48 Gy/8 fractions/5 days or 54 Gy/9 f ractions/5 days. Acute toxicity was scored using the Radiation Therapy Onco logy Group (RTOG) radiation morbidity scoring criteria. Median follow-up ti me was 31 months. Results: HDR brachytherapy as a monotherapy was well-tolerated. No signific ant intra- or peri-operative complications occurred. No patient experienced acute toxicity of grade 3 or more. PSA levels normalized in 95% of patient s within 20 months after irradiation. Four-year clinical and biochemical re lapse-free rates were 95% and 55%, respectively. Conclusion: Acute toxicity with this method was acceptable. Further patient accrual and longer follow-up will allow comparison to other techniques. (C ) 2000 Elsevier Science Inc.