S1260
Clinical - Urology
ESTRO 2026
Saudi Arabia. 4 Radiation Oncology, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
identified throughout the follow-up period. Conclusion:
Purpose/Objective: This study investigates whether omitting presacral lymph node irradiation during definitive external- beam radiation therapy for non-metastatic prostate cancer affects locoregional control or treatment- related toxicity. We hypothesized that selective omission of the presacral region would maintain oncologic efficacy while reducing toxicity, supporting a more tailored approach to pelvic nodal irradiation. Material/Methods: This retrospective single-institution study analyzed 124 patients with non-metastatic prostate cancer treated with definitive external-beam radiation therapy between 2012-2024, where the presacral region was deliberately excluded from the clinical target volume. The cohort had a mean age of 76.5 years (range: 55- 96), with 65.3% classified as high-risk according to National Comprehensive Cancer Network criteria. Treatment included various fractionation schedules ranging from 3500-7400 cGy, with 7200 cGy in 36 fractions being most common (66.9% of patients). Androgen-deprivation therapy was administered to 79% of patients. The elective nodal clinical target volume covered internal iliac, external iliac, and obturator nodal chains, but intentionally excluded the presacral region. Key endpoints included locoregional control, distant metastasis-free survival, overall survival, and toxicity profiles graded according to Common Terminology Criteria for Adverse Events version 4.0. Statistical analysis was performed using Kaplan-Meier method for survival outcomes and chi- square or Fisher's exact test for toxicity comparisons. Results:
Omitting presacral lymph node irradiation in definitive radiation therapy for prostate cancer achieved excellent locoregional control with no presacral failures, even in a predominantly high-risk cohort. This approach was associated with a favorable toxicity profile, including complete resolution of severe dysuria and low gastrointestinal toxicity. These findings support selective omission of presacral irradiation as a safe strategy that may reduce treatment-related toxicities while maintaining oncologic outcomes. Prospective validation in larger cohorts is warranted. References: De Meerleer G, et al. Elective nodal radiotherapy in prostate cancer. Lancet Oncol. 2021;22(6):e257- e267.2.Spratt DE, et al. Patterns of lymph node failure after dose-escalated radiotherapy. Eur Urol. 2017;71(1):37-43.3.Roscigno M, et al. Extent of lymph node dissection in intermediate- and high-risk prostate cancer. Eur Urol. 2018;73(5):684-692.4.Murthy V, et al. Late toxicity with prostate only or whole pelvic radiation therapy (POP-RT). Radiother Oncol. 2020;148:153-160.5.Wang K, Tepper JE. Radiation therapy-associated toxicity. CA Cancer J Clin. 2021;71(5):437-454. Keywords: Prostate, Presacral Lymph Nodes, Sparing Digital Poster 3376 Feasibility of MR-Linac guided SBRT reirradiation for macroscopic local recurrence after prostatectomy and prior radiotherapy. Beatriz Moreno Fuentes 1 , Inmaculada Navarro Domenech 1 , Alonso La Rosa De los Rios 1 , Ana Castaño Cantos 1 , Laura Zaragoza Cocero 1 , Luis Glaria Enriquez 1 , Carlos Ferrer Gracia 2 , Rosa Maria Morera Lopez 1 1 Radiation oncologist, Hospital Universitario La Paz, Madrid, Spain. 2 Radiophysics and radiation protection, Hospital Universitario La Paz, Madrid, Spain Purpose/Objective: Macroscopic local recurrence after radical prostatectomy (RP) and/or prior external beam radiotherapy (EBRT) or low-dose-rate brachytherapy (LDR-BT) poses a significant clinical challenge. Next-
At a median follow-up of 47.0 months (range: 3-145.8), the 10-year locoregional control rate was 99.2%. Only two regional failures were observed at 23.8 and 125.1 months, neither involving the presacral region. The 10-
year overall survival rate was 95.2%. Distant metastasis developed in 8 patients (6.5%),
predominantly involving osseous sites (87.5%). Toxicity analysis demonstrated complete resolution of severe dysuria in all affected patients (9.7% pre-treatment to 0% post-treatment). Gastrointestinal toxicity remained low, with improvement in diarrhea rates from 27.4% to 14.5%. Erectile function was preserved in 70% of potent patients at baseline. No presacral failures were
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