Main Session
Sep 30
QP 37 - From Detection to Re-treatment: Managing Radiorecurrent Prostate Cancer

1220 - Salvage High-Dose-Rate Brachytherapy after Prior Prostate Radiotherapy: Contemporary Multi-Institutional Outcomes in 236 Patients

08:20am - 08:25am ET
Room 253

Presenter(s)

Mateusz Bilski, MD, PhD Headshot
Mateusz Bilski, MD, PhD - Lublin Region Oncology Center, Lublin, lubelskie

M. Bilski1,2, G. Salfi3, A. Gomez De Iturriaga4, P. Saniewski5, M. Stankiewicz6, D. Buchser7, F. Mastroleo8, T. Soeterik9, P. Garlatti10, M. Aquilano11, G. Francolini11, B. A. Jereczek-Fossa12, T. Zilli13, and M. Pedrani14; 1Affidea Nu-med Center of Oncology Diagnostics and Therapy, Zamosc, Poland, 2Department of Radiotherapy, Medical University of Lublin, Lublin, Poland, 3Oncology Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona, Switzerland; Institute of Oncology Research, Bellinzona, Switzerland, 4Cruces Unisersity Hospital / Biocruces Health Research Institute, Spain, Bilbao, Spain, 5Radiotherapy Department. Maria Sklodowska-Curie Institute-Oncology Centre, Warsaw, Poland, 6Brachytherapy Department, Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice, Poland, 7Hospital Universitario de Cruces, Barakaldo, Spain, 8Division of Radiation Oncology, IEO, European Institute of Oncology, IRCCS, Milan, Italy, 9Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, Netherlands, 10Radiation Oncology, Careggi University Hospital, University of Florence, Florence, Italy, 11Radiation Oncology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, Florence, Italy, 12Division of Radiation Oncology, IEO, European Institute of Oncology IRCCS, Via Ripamonti 435, I 20132, Milano, Italy, 13Department of Radiation Oncology, Oncology Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona, Switzerland, 14Oncology Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona, Switzerland

Purpose/Objective(s): Salvage HDR prostate brachytherapy after prior radiotherapy is a potentially curative, organ-preserving option for locally recurrent prostate cancer. Contemporary multicenter data from the PSMA PET era with detailed toxicity and time-to-event outcomes remain limited.

Materials/Methods: We retrospectively analyzed 236 consecutive patients from four centers treated with salvage HDR brachytherapy for PSMA PET- and MRI- and/or biopsy-proven local recurrence after prior prostate radiotherapy. Missing data were handled using multiple imputation; descriptive results are reported from the first imputed dataset (n=236). Baseline characteristics, imaging use, and primary radiotherapy type were summarized. Relapse-free survival (RFS), time to next systemic therapy (TTNS), and overall survival (OS) were estimated using Kaplan–Meier methods. Acute and late genitourinary (GU) and gastrointestinal (GI) toxicity were graded per CTCAE, with binary endpoints for grade =2 and =3 events.

Results: Median age at salvage brachytherapy was 73 years (IQR 69–77). PSMA PET was used in 76%. Primary radiotherapy included conventional EBRT (32%), moderately hypofractionated EBRT (44%), SBRT (3%), brachytherapy monotherapy (19%), and EBRT+boost (3%). ADT at recurrence was given in 68%. After salvage, 71% achieved PSA nadir <0.2 ng/mL. At a median follow-up of 43.7 months, median RFS was 64.1 months (95% CI 54.1–86.0); 5- and 10-year RFS were 52.9% and 16.8%. Median TTNS was 87.2 months; 68 patients initiated systemic therapy. Median OS was 124.4 months; 5- and 10-year OS were 85.4% and 57.9%, with 35 deaths overall. Acute GU grade =2 toxicity occurred in 26.7% (grade 3: 0.4%); acute GI grade =2 in 3.0% (no grade =3). Late GU grade =2 and =3 toxicity occurred in 44.5% and 12.3%, respectively. Late GI grade =2 and =3 toxicity was 3.0% and 1.3%.

Conclusions: In this contemporary multicenter cohort, salvage HDR brachytherapy achieved deep biochemical responses and durable disease control, with median RFS exceeding 5 years and median TTNS beyond 7 years. Five-year OS was 85%. Late grade =3 GU toxicity occurred in 12%, while severe GI toxicity was rare. Salvage HDR brachytherapy represents an effective organ-preserving strategy in carefully selected patients with locally recurrent prostate cancer after radiotherapy.

Conclusion: In this multicenter cohort of salvage prostate brachytherapy after diverse primary radiotherapy regimens, most patients achieved deep biochemical responses, with >70% reaching a PSA nadir <0.2 ng/mL. Median RFS was 5.3 years (53% at 5 years; 17% at 10 years), and median TTNS exceeded 7 years. Five-year OS rates were 85%. Late grade =3 GU toxicity occurred in 12%, while GI toxicity was infrequent and mainly low grade. Salvage brachytherapy appears to be an effective organ-preserving option in carefully selected patients with locally recurrent prostate cancer after radiotherapy.