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

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.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.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.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.