ESTRO 2025 - Abstract Book

S1954

Clinical - Urology

ESTRO 2025

bifurcation) with up to 5 suspect lymph nodes. Reirradiation was defined according to the ESTRO-EORTC consensus on re-irradiation as an irradiation with a geometrical overlap with a previous course of RT.

Results: A total of 150 patients relapsing on 192 nodal sites were retrospectively included, from 13 French centers. Ninety seven percent of the patients were staged with positron emission tomography/ computed tomography (PET/CT). The majority of patients (80.7%) received radical prostatectomy as primary treatment. The median number of lymph node per patient was 1, and the median planning target volume (PTV) size was 6.2cc. After a median follow-up of 30.5 months, late grade 2 and grade 3 GI and GU toxicity occurred in respectively 1.9%, 0% and 7.1% and 2.6% of the cases. The 2-years and 3-years radiological progression-free survival (rPFS) reached respectively 44.6% (95% CI: 36.2% - 55%) and 32.9% (95% CI: 24.8% – 43.6%). In multivariate analysis, previous treatment with ADT, concomitant ADT and PSA nadir following SBRT was associated with rPFS. The 2-years and 3-years androgen deprivation therapy free survival (ADT-FS) reached respectively 59.8% (95% CI: 51.2% - 69.9%) and 43.4% (95% CI: 34.3% – 54.9%). In multivariate analysis, previous treatment with ADT was associated with worse ADT-FS. In patients experiencing biochemical relapse, further PNMOR occurred in up to a third of the cases. Conclusion: The CYGNUS retrospective study supports the safety of reirradiation with SBRT for PNMOR. Oncological outcomes are encouraging. Long-term results from the ReCare prospective cohort are eagerly awaited to provide high-quality data on reirradiation with SBRT. Proffered Paper PEACE V-STORM Salvage Treatment of OligoRecurrent nodal prostate cancer Metastases: treatment management of loco-regional relapses and quality of life Thomas Zilli 1,2 , Shankar Siva 3 , Sigmund Brabrand 4 , Piet Dirix 5 , Nick Liefhooghe 6 , Jean Francois Otte 7 , Alfonso Gomez Iturriaga 8 , Wouter Everaerts 9 , Mohamed Shelan 10 , Antonio Conde-Moreno 11 , Fernand López Campos 12 , Alexandros Papachristofilou 13 , Matthias Guckenberger 14 , Marta Scorsetti 15 , Almudena Zapatero 16 , Ana-Elena Villafranca Iturre 17 , Clara Eito 18 , Felipe Couñago 19 , Paolo Muto 20 , Wim Dutoy 21 , Nicolas Mach 22 , Valérie Fon 23 , Els Goetghebeur 24 , Dries Reynders 24 , Piet Ost 25,5 1 Radiation Oncology, Geneva University Hospital, Geneva, now at IOSI - EOC, Bellinzona, Geneva, Switzerland. 2 Faculty of Medicine, Geneva University, Geneva, Switzerland. 3 Radiation Oncology, 3. Epworth Healthcare, ICON Cancer Centre and Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Australia, Melbourne, Australia. 4 Radiation Oncology, 4. Oslo University Hospital, Oslo, Norway. 5 Radiation Oncology, Iridium Network, Wilrijk, Belgium. 6 Radiation Oncology, AZ Groeninge, Kortrijk, Belgium. 7 Radiation Oncology, 6. Jules Bordet Institute, Bruxelles, Belgium. 8 Radiation Oncology, 7. Hospital Universitario Cruces, Barakaldo, Spain. 9 Urology, 8. University Hospitals Leuven and Department of cellular and Molecular Medicine, KU Leuven, Leuven, Belgium. 10 Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland. 11 Radiation Oncology, 10. Hospital Universitari i Politècnic la Fe, Valencia, Switzerland. 12 Radiation Oncology, 11. Hospital Universitario Ramón y Cajal, Madrid, Spain. 13 Radiation Oncology, 12. Universitätsspital Basel, Basel, Switzerland. 14 Radiation Oncology, 13. University Hospital Zurich, University of Zurich, Zürich, Switzerland. 15 Radiation Oncology, 14. Humanitas Clinical and Research Hospital, IRCSS, Radiotherapy and Radiosurgery Department, Rozzano, Italy. 16 Radiation Oncology, Health Research Institute, University Hospital La Princesa, Madrid, Spain. 17 Radiation Oncology, 16. Complejo Hospitalario de Navarra, Navarra, Spain. 18 Radiation Oncology, 17. Instituto Oncólogico Clinica Universitaria IMQ, Bilbao, Spain. 19 Radiation Oncology, 18. University Hospital Quironsalud and Universidad Europea de Madrid, Madrid, Spain. 20 Radiation Oncology, 19. Napoli Istituto Nazionale Tumori IRCCS Fondazione Pascale, Napoli, Italy. 21 Radiation Oncology, 20. AZ St-Lucas Ghent, Ghent, Belgium. 22 Medical Oncology, Geneva Keywords: prostate, oligorecurrent, reirradiation 1579