ESTRO 2025 - Abstract Book

S384

Brachytherapy - Urology

ESTRO 2025

1 Department of Radiation Oncology, Meixoeiro Hospital, Vigo, Spain. 2 Department of Radiation Oncology, Navarra University Hospital, Pamplona, Spain. 3 Department of Radiation Oncology, La Fe University Hospital, Valencia, Spain. 4 Department of Radiation Oncology, Cruces Hospital, Barakaldo, Spain. 5 Department of Radiation Oncology, Benidorm Hospital, Benidorm, Spain. 6 Department of Radiation Oncology, Oncologikoa Foundation, Guipuzkoa. Donostia, Spain. 7 Department of Radiation Oncology, Reina Sofía University Hospital, Córdoba, Spain. 8 Department of Radiation Oncology, Ramón y Cajal Hospital, Madrid, Spain. 9 Department of Radiation Oncology, Lozano Blesa Hospital, Zaragoza, Spain. 10 Department of Radiation Oncology, Asturias Central University Hospital, Oviedo, Spain

Purpose/Objective: This study aims to evaluate the results of Salvage Prostate Brachytherapy across 10 hospitals in Spain.

Material/Methods: A retrospective analysis was performed on the outcomes of salvage brachytherapy (BT) for prostate cancer at 10 Spanish hospitals. Survival rates were modeled using Kaplan-Meier curves, and comparisons between different strata were conducted using the Log-Rank test. Results: 161 patients were included. The mean age of the patient was 71.4 years (±5.8), and the mean follow-up was 51 months. We included patients treated with HDR (16-20 Gy) and LDR (110-145 Gy). The diagnostic techniques were also MRI in the older patients and choline PET in the more recent ones. The cumulative survival rate free of regional recurrence at 5 years (60 months) was 90%, with the mean time to regional recurrence being 109.9 months (9 years). 95% CI (102,116). The cumulative survival rate free of metastatic relapse at 5 years (60 months) is 80%, with the mean time to metastatic recurrence being 102.8 months (8.6 years) 95% CI (94,111). Statistically significant factor for better metastatic relapse rates included a Gleason score below 8 and an LDR dose above 125 Gy for BF. No significant differences in survival were observed between HDR and LDR techniques. Although the Phoenix criterion is the most widely used, a non-significant benefit has been found in pelvic (p=0.168) and metastatic (p=0.469) relapse in patients with an early diagnosis, With respect to the dose we have observed differences with less than 125 Gy (LDR) and 2 fractions of 10,11 and 12 Gy in HDR had a shorter time to metastatic recurrence (p<0.1) and the same for patients with PSA greater than 5 ng/ ml prior to rescue treatment (p<0,1). Cystitis was greater in patients treated with HDR-BT with a dose of 3 times 10 Gy (p<0.001). Conclusion: BT as a salvage treatment offers effective local and distant control, particularly in patients without high-risk features. However, we found differences between doses, techniques and imaging tests that may be decisive in the evolution of the patients disease. Although not statistically significant, treatment before reaching the Phoenix criterion may be associated with a benefit in pelvic and metastatic progression-free survival.

Keywords: Salvage, prostate, brachytherapy

References: 1. Piotr Wojcieszek et al. Salvage high-dose-rate brachytherapy for locally recurrent prostate cancer after primary radiotherapy failure. Radiotherapy Oncology. 2016 Jun;119(3):405-10. 2. Iván Henríquez López et al. Salvage brachytherapy for locally-recurrent prostate cancer after radiation therapy: A comparison of efficacy and toxicity outcomes with high-dose rate and low-dose rate brachytherapy. Radiotherapy and Oncology 141 (2019) 156–163.