Four-year outcomes of hypofractionated high-dose-rate prostate brachytherapy and external beam radiotherapy

PURPOSE: High-dose-rate (HDR) brachytherapy boost in prostate cancer allows dose escalation and delivery of higher biologically effective dose (BED). We evaluated the outcomes of intensitymodulated radiation therapy (IMRT) and HDR boost in a community setting. METHODS AND MATERIALS: Between July 2003 and April 2008, 148 patients with prostate cancer were treated at Cancer Center of Irvine using two transperineal implants performed 1 week apart (22 Gy delivered in four fractions divided between two insertions and delivered twice daily), followed by IMRT (50.4 Gy). Hormonal therapy was given for 1 year to all patients with Gleason score of 8 or higher. RESULTS: Patient characteristics are as follows: median age at treatment, 71 years; American Joint Committee on Cancer Group 103, 53%; Gleason score of 7, 41%; and Gleason score of 8 or higher, 14%. Median followup was 49 months, and median prostate-specific antigen (PSA) nadir was 0.15 ng/InL. The 4-year actuarial biochemical disease-free survival (bDFS) was 96.8/81% by Phoenix/PSA lower than 0.5 ng/mL criteria. According to National Comprehensive Cancer Center Clinical Practice Guidelines defined recurrence risk groups, 4-year bDFS for low risk was 100/ 92.9%, intermediate risk was 100/86.7%, and high risk was 94/75.4% by Phoenix/PSA lower than 0.5 ng/mL criteria. No statistically significant difference in bDFS was detected by either failure criteria based on risk group, lymph node risk, or initial PSA. Treatment was well tolerated. Subacute/late genitourinary and gastrointestinal toxicities were limited to 10% and 5%, respectively of all patients. CONCLUSIONS: Prostate IMRT plus HDR brachytherapy boost was well tolerated with appropriate PSA response and bDFS at 4 years, demonstrated in a community setting. This treatment schema provides a high BED, comparable with hypofractionated prostate regimens previously reported in the literature. Higher BED delivery should be explored in further dose escalation studies. (C) 2013 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.