ESTRO 2025 - Abstract Book

S2028

Clinical - Urology

ESTRO 2025

Moreover, ENRT compensates for the higher disease burden, and clinical recurrence is no higher than in oligometastatic disease treated with MDT.

Keywords: Prostate Cancer, Lymph Nodes

References: 1. De Bleser E, et al. Metastasis-directed Therapy in Treating Nodal Oligorecurrent Prostate Cancer: A Multi institutional Analysis Comparing the Outcome and Toxicity of Stereotactic Body Radiotherapy and Elective Nodal Radiotherapy. Eur Urol 2019; 76(6): 732-739 2. Fodor A, et al. Extended Nodal Radiotherapy for Prostate Cancer Relapse Guided with [11C]-choline PET/CT: ten-year results in patients enrolled in a prospective trial. Eur J Nucl Med Mol Imaging 2024; 51(2): 590-603 3. Aggarwal R, et al. PRESTO: A phase III, open-label study of intensification of androgen blockade in patients with high-risk biochemically relapsed castration-sensitive prostate cancer (AFT-19). J Clin Oncol 2024; 42 (10): 1114-1123

3039

Digital Poster A single institution study of efficacy and toxicity outcomes of spinal SBRT in prostate cancer Binnaz Yasar 1,2 , Helen Taylor 1 , Yae-Eun Suh 1 , Vincent Khoo 1,2 , Rosalind Eeles 3,1 , Alison Tree 1,2 , Julia Murray 1,2 , Nicholas van As 1,2 1 Radiotherapy Department, Royal Marsden NHS Foundation Trust, London, United Kingdom. 2 Urology Research, The Institute of Cancer Research, London, United Kingdom. 3 Department of Oncogenetics, The Institute of Cancer Research, London, United Kingdom Purpose/Objective: We report local control and toxicity rates of spinal stereotactic body radiotherapy (SBRT) in men with prostate cancer (PCa) at a large tertiary centre. Published one-year control rates for spinal SBRT range from 65-90% and vertebral compression fracture (VCF) rates vary from 10-15%. 1,2 Limited data exist on predictors of VCF after spinal SBRT in PCa. Material/Methods: A retrospective review was undertaken of patients with PCa referred for spinal SBRT from November 2011 to November 2023 with at least 12months follow-up. All patients were treated on the CyberKnife platform. Data were collected on patient and treatment demographics, and toxicity. Imaging was conducted on biochemical relapse or symptoms. Logistic regression was undertaken to assess predictors of VCF. Time to biochemical, local and distant metastasis (DM) was performed using Kaplan Meier and log-rank analysis. Results: A total of 91 PCa patients were treated with spinal SBRT. Median follow-up was 54 months. Median age was 69 years and median pre-SBRT PSA was 2.34 (IQR 0.9-5.7). 60 patients were treated with concurrent ADT (66%). 63 patients had 30Gy/3fractions (69%) and median BED was 230 (range 150-230). 72 patients had oligometastases (79%) and 19 had oligoprogression (21%). Radiological VCF rate was 8% (7/91) and 57% were asymptomatic (4/7). Median time to VCF was 38.5 months. Age ≥70 years was associated with increased VCF risk with 4.2 times higher likelihood (p = 0.048). Spinal level, bone pain, spinal instability score (SINS) score, and fractionation were not significantly associated with VCF risk. Median SINS scores were overall low at 3. There were no cases of radiation myelopathy. One-year local control rate was 93% and 3-year local control was 88%. Median bPFS was 14 months and median time to local or distant progression was 20 months. For oligometastatic disease, there was no significant difference in bPFS, time to DM and OS with concurrent short course ADT versus no ADT use, when adjusted for testosterone