S1265
Clinical - Urology
ESTRO 2026
lesion), primarily located in lymph nodes (55.2%) and bones (40.5%). Hypofractionated RT was delivered in 30.2% of lesions, while 69.8% received conventional fractionation.The 2-year LC rate was 91.3%, with a 5- year LC of 85.3%. Mean LC duration was 39.9 months. The mean PFS was 30.3 months, with cumulative 2-, 3-, 5-, and 10-year PFS rates of 63.0%, 50.8%, 50.8%, and 48.2%, respectively. Out-of-field progression occurred gradually, with cumulative rates of 28.4%, 36.2%, 38.0%, and 38.8% at 2, 3, 5, and 10 years. Conclusion: Metastasis-directed stereotactic radiotherapy provides durable local control and meaningful systemic disease stabilization in oligometastatic prostate cancer. Long- term outcomes indicate sustained local efficacy with a moderate risk of distant progression, supporting SRT as an effective treatment option within a multimodal management strategy for selected patients. References: Persson AE, Hallqvist A, Bjørn Larsen L, Rasmussen M, Scherman J, Nilsson P, Tønnesen H, Gunnlaugsson A. Stereotactic body radiotherapy as metastasis-directed therapy in oligometastatic prostate cancer: a systematic review and meta-analysis of randomized controlled trials.Radiother Oncol. 2024;19:173.Fiorica F, et al. Metastasis-Directed Therapy in Oligometastatic Prostate Cancer.Cancers (Basel). 25;17(8):1256.Marvaso G, Volpe S, Pepa M, Augugliaro M, Corrao G, Biffi A, et al. ADT with SBRT versus SBRT alone for hormone-sensitive oligometastatic prostate cancer.Lancet Oncol. 2025.Alzibdeh A, et al. Metastasis-Directed Stereotactic Body Radiation Therapy for Oligometastatic Prostate Cancer: Outcomes in 200 Patients.J Clin Oncol (GO). 25. Keywords: Oligometastatic Prostate Cancer Effect on White Blood Cell Subpopulations and Acute Adverse Events Analysis of 2- vs 5-Fraction SBRT with DIL Boost in Prostate Cancer: A DOTA-2 Study Ratchapas Romrattaphan, Pittaya Dankulchai, Tissana Prasartseree, Wiwatchai Sittiwong, Wajana Thaweerat, Suchada Junlabut, Supamon Nitipitch, Naritsa Rotmuenwai Division of Radiation Oncology, Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand Purpose/Objective: To analyse the effect on white blood cell (WBC) subpopulations and update acute adverse events (AEs) from DOTA-2 RCT comparing two ultra- hypofractionated SBRT schedules. Material/Methods: Digital Poster 3480
risk, hypertension was not associated with metastatic disease in high-risk patients or low- and intermediate- risk patients. 142 genes were differentially expressed for hypertension status at diagnosis of prostate cancer (p-value < 0.01), of which 4 were also differentially expressed in relation to metastatic disease (p-value < 0.01). Immune and stromal cell type estimation scores and Hallmark gene sets were not differentially expressed for hypertension status at diagnosis of prostate cancer. Conclusion: Hypertension was associated with lower risk of metastatic disease in patients with high-risk prostate cancer, but not in low-and intermediate-risk disease. Our ongoing analysis will aim to validate these findings in separate independent prostate cancer cohorts and to assess whether the observed associations are influenced by antihypertensive medication use prior to diagnosis. Using hypertension as a surrogate for antihypertensive medication usage, our analysis could potentially suggest antihypertensive medication as repurposed, preventative therapeutics for high-risk prostate cancer. Keywords: Prostate cancer, Metastatic disease, Hypertension Digital Poster 3471 Metastasis-Directed Stereotactic Radiotherapy in Oligometastatic Prostate Cancer: Patient Characteristics and Long-Term Outcomes Kerem Tuna Tas, Phillip Lishewiski, Edgar Smalec, Hilke Vorwerk, Adeberg Sebastian, Ahmed Gawish epartment of Radiotherapy and Radiation Oncology, Marburg University Hospital, Marburg, Germany Purpose/Objective: This study evaluated the clinical characteristics and treatment outcomes of patients with oligometastatic prostate cancer treated with metastasis-directed stereotactic radiotherapy (SRT). Material/Methods: A total of 103 patients with 116 metastatic lesions treated between January 2015 and July 2024 were retrospectively analyzed. Median follow-up was 46.3 months (range, 6–189). Patient-, tumor-, and treatment-related parameters were assessed, including PSA kinetics, previous therapies, and the extent of disease. Local control (LC), progression-free survival (PFS), and out-of-field progression (OFP) were evaluated using Kaplan–Meier estimates. Results: At initial diagnosis, 69.9% of patients underwent prostatectomy, and 77.7% received prostate/prostatic bed RT before metastasis-directed therapy. Most patients (93.2%) had ≤ 3 metastases (59.2% single
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