ESTRO 2025 - Abstract Book

S2128

Clinical - Urology

ESTRO 2025

4370

Digital Poster Prostate cancer outcomes following salvage treatment and risk factors for biochemical recurrence: An Audit Matthew Bradford, Nina Liebenburg, Christos Mikropoulos, Clare Williamson Oncology, Royal Surrey Foundation Trust, Guildford, United Kingdom Introduction : Despite having an excellent prognosis, patients with localised prostate cancer experience significant rates (20-40%) (1) of biochemical recurrence (BR) following radical prostatectomy. (RP) The standard treatment approach for BR is radical radiotherapy (EBRT) This audit assesses the effectiveness and side effects of differing radiotherapy strategies for recurrent localised prostate cancer within a regional cancer centre, along with risk factors for BR after both RP and EBRT and the outcomes of Stereotactic Radiotherapy amongst this cohort. Methods : Between 15/1/2020 and 14/12/2021 patients (N=102) were identified who had undergone RP and experienced primary BR. All patients received salvage radiotherapy to the prostate bed, but not all had radiotherapy delivered to the pelvic lymph nodes. Rates of secondary BR in these different treatment groups were then ascertained. Risk factors for both primary and secondary BR were assessed including age, surgical gleason score, nodal involvement, surgical margins and surgical tumour staging. All data was identified from medical records and analysed in excel. Results : 102 patients were identified. No histology was found for 15 patients, leaving 87 that underwent full analysis. Similar rates of secondary BCR were found comparing patients who underwent prostate bed (18%) with prostate bed and lymph node (20%) radiotherapy. In patients with very high risk surgical gleason score, mean time to detectable PSA following radical prostatectomy was 6 months; 80% had radiotherapy to the prostate bed and nodes following which 35% had secondary BCR. Overall, the higher the first detectable PSA post prostatectomy, the higher the percentage of patients having secondary BCR and lower the disease-free interval after radiotherapy. 44% and 36% of patients with perineural and lymphovascular invasion on histology progressed to secondary BCR. In a regression analysis, no statistically significant outcome was identified. Conclusion : The higher the first detectable PSA in a patient post RP, the higher the risk of developing secondary BCR following prostatic radiotherapy. Both perineural and lymphovascular invasion increased likelihood of secondary BCR. Results suggest there may be no difference in use of prostate bed and prostate bed with nodal radiotherapy in primary BCR post RP. Our findings highlight the lack of data to support high-risk patients who present with BCR post RP. The use of hormones may have reduced the rates of secondary BCR we recommend investigating this. The use of SABR in secondary BCR will be reviewed with routine PSMA scanning and lower laboratory assays picking up potential BCR at an earlier stage. References: 1. Stensland KD, Caram MEV, Herr DJ, Burns JA, Sparks JB, Elliott DA, et al. National Long-term Survival Estimates After Radical Prostatectomy for Prostate Cancer. Urology. 2024;184:135-41. 2. Simon NI, Parker C, Hope TA, Paller CJ. Best Approaches and Updates for Prostate Cancer Biochemical Recurrence. Am Soc Clin Oncol Educ Book. 2022;42:1-8. 3. Brodowsky EC, Sood A, Butaney M, Majdalany SE, Stephens A, Corsi N, Piontkowski AJ, Rakic I, Jamil M, Dalela D, Peabody JO, Rogers CG, Abdollah F. Time to second biochemical recurrence as a prognostic indicator in postprostatectomy patients who undergo salvage radiation therapy: An RTOG 9601 based post hoc analysis. Keywords: Prostate, Salvage, Outcomes