A Prospective Study of Magnetic Resonance Imaging-guided Focal Salvage High-dose-Rate Brachytherapy for Radiorecurrent Prostate Cancer: Updated Results of 30 Patients

Purpose: Limited prospective data on focal salvage high-dose-rate (HDR) prostate brachytherapy is available. We sought to explore the toxicities, health-related quality of life (HRQoL), and efficacy of focal salvage HDR brachytherapy in a prospective clinical trial. This report presents the updated results of previously published data. Methods and Materials: Patients with locally recurrent prostate cancer after previous external beam radiation therapy and/or brachytherapy were enrolled. Patients received magnetic resonance imaging (MRI)-guided, ultrasound-based focal HDR brachytherapy delivered over 2 fractions of 13.5 Gy delivered 1 to 2 weeks apart. Androgen deprivation therapy (ADT) was not used. Results: Thirty patients were treated between 2012 and 2019. At a median follow-up time of 39 months, the 3-year biochemical failure-free rate was 61.8% (95% confidence interval, 44.0%-86.6%), and the 3-year ADT/salvage therapy-free rate was 86.0% (95% confidence interval, 74.1%-99.8%). Seventeen patients experienced subsequent biochemical failure, 9 received ADT and/or further local salvage, and no patients died of prostate cancer. Of the 28 patients who had posttreatment MRI, 26 had a local treatment response. No acute grade >= 3 genitourinary/gastrointestinal toxicity was observed. One temporary late grade 3 genitourinary toxicity event occurred, but no late grade >= 3 gastrointestinal toxicity was seen. No significant decline in urinary or bowel HRQoL was observed. Conclusions: Focal salvage HDR brachytherapy has a favorable side effect profile, no significant decline in HRQoL, and the 3-year biochemical control rates are in line with those of other salvage options. Early MRI response at the treated site is common, but does not preclude subsequent biochemical failure. (c) 2022 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.