Phase I/II trial of single-fraction high-dose-rate brachytherapy-boosted hypofractionated intensity-modulated radiation therapy for localized adenocarcinoma of the prostate

PURPOSE: A Phase I/II protocol was conducted to examine the toxicity and efficacy of the combination of intensity-modulated radiation therapy (IMRT) with a single-fraction high-dose-rate (HDR) brachytherapy implant. METHODS AND MATERIALS: From 2001 through 2006, 26 consecutive patients were treated on the trial. The primary objective was to demonstrate a high rate of completion without experiencing a treatment-limiting toxicity. Eligibility was limited to patients with T stage <= 2b, prostate-specific antigen (PSA) <= 20, and Gleason score <= 7. Treatment began with a single HDR fraction of 6 Gy to the entire prostate and 9 Gy to the peripheral zone, followed by IMRT optimized to deliver in 28 fractions with a normalized total dose of 70 Gy. Patients received 50.4 Gy to the pelvic lymph node. The prostate dose (IMRT and HDR) resulted in an average biologic equivalent dose >128 Gy (alpha/beta = 3). Patients whose pretreatment PSA was >= 10 ng/mL, Gleason score 7, or stage >= T2b received short-term androgen ablation. RESULTS: Median followup was 53 months (9-68 months). There were no biochemical failures by either the American Society of Therapeutic Radiology and Oncology or the Phoenix definitions. The median nadir PSA was 0.32 ng/mL. All the 26 patients completed the treatment as prescribed. The rate of Grade 3 late genitourinary toxicity was 3.8% consisting of a urethral stricture. There was no other Grade 3 or 4 genitourinary or gastrointestinal toxicities. CONCLUSIONS: Single-fraction HDR-boosted IMRT is a safe effective method of dose escalation for localized prostate cancer. (C) 2012 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.