Author: Elizabeth K. Butker, Cara Cimmino, Jenna L. Fair, David Matthew Giles, Bruce Hershatter, Shadab Momin, Sagar Patel, John Pattaras, Kamran Salari Salari, Aaron Weiss 👨🔬
Affiliation: Department of Radiation Oncology and Winship Cancer Institute, Emory University, Emory University School of Medicine 🌍
Purpose: Prostate cancer patients may experience a local-only failure after radiation. While high-dose-rate (HDR) brachytherapy may have more favorable toxicity profile and cancer control compared to other forms of salvage, the optimal salvage HDR brachytherapy treatment regimen, including number of fractions and dose, is evolving. We present toxicity and efficacy using a two-fraction whole gland salvage regimen with focal intraprostatic boost using HDR brachytherapy.
Methods: There were 26 consecutive patients who underwent salvage prostate HDR brachytherapy at a single institution between 2019-2022. All patients met Phoenix criteria and underwent molecular imaging with mpMRI and either fluciclovine or PSMA PET CT. All patients underwent two implants. We used all available information to define high-risk clinical target volume (HRCTV): the area of tracer uptake on PET/CT, systematic biopsy, and/or mpMRI. The HRCTV received 13.5 Gy and the remainder of the gland received 9 – 10 Gy per implant. Patients were followed at 4 weeks, then every 3-6 months. Acute and late genitourinary and GI toxicities were graded based on CTCAE 4.0. PSA was measured at each follow-up; refractory PSA prompted subsequent cross-sectional and molecular imaging.
Results: The median follow-up time following salvage HDR brachytherapy was 21 months in this study. Acute grade 2 and late grade 2 genitourinary toxicity was 38% and 31%, respectively, acute and late grade 3 genitourinary toxicity was 15% and 4%, respectively. No Grade 4 acute or late genitourinary toxicity was reported. No gastrointestinal toxicities were seen. Two patients experienced a refractory/recurrent PSA; no patient experienced a local relapse; 2 patients experienced regional and/or distant recurrence.
Conclusion: Two-fraction HDR salvage technique utilizing reduced-dose whole gland therapy with focal intraprostatic boost is feasible and results in acceptable toxicity and excellent control.