ESTRO 2025 - Abstract Book

S4411

Late-breaking abstracts

ESTRO 2025

4974

Proffered Paper PEACE V – Salvage Treatment of OligoRecurrent nodal prostate cancer Metastases (STORM), a randomized phase II trial: report of the primary endpoint Thomas Zilli 1,2 , Shankar Siva 3,4 , Sigmund Brabrand 5 , Piet Dirix 6 , Nick Liefhooghe 7 , François-Xavier Otte 8 , Alfonso Gomez-Iturriaga 9 , Wouter Everaerts 10 , Mohamed Shelan 11 , Antonio Conde-Moreno 12 , Fernando López Campos 13 , Alexandros Papachristofilou 14 , Matthias Guckenberger 15 , Marta Scorsetti 16 , Almudena Zapatero 17 , Ana-Elena Villafranca Iturre 18 , Clara Eito 19 , Felipe Couñago 20 , Paolo Muto 21 , Wim Duthoy 22 , Nicolas Mach 23 , Valérie Fonteyne 24,25 , Els Goetghebeur 26 , Dries Reynders 26 , Piet Ost 6,25 1 Radiation Oncology, Oncology Institute of Southern Switzerland, EOC, Bellinzona, Switzerland. 2 Radiation Oncology, Geneva University Hospital (previous institution), Geneva, Switzerland. 3 Radiation Oncology, Epworth Healthcare, ICON Cancer Centre, Melbourne, Australia. 4 Radiation Oncology, Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Australia. 5 Radiation Oncology, Oslo University Hospital, Oslo, Norway. 6 Radiation Oncology, Iridium Network, Wilrijk, Belgium. 7 Radiation Oncology, AZ Groeninge, Kortrijk, Belgium. 8 Radiation Oncology, Jules Bordet Institute, Brussels, Belgium. 9 Radiation Oncology, Hospital Universitario Cruces, Barakaldo, Spain. 10 Urology, University Hospitals Leuven and Department of cellular and Molecular Medicine, KU Leuven, Leuven, Belgium. 11 Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland. 12 Radiation Oncology, Hospital Universitari i Politècnic la Fe, Valencia, Spain. 13 Radiation Oncology, Hospital Universitario Ramón y Cajal, Madrid, Spain. 14 Radiation Oncology, Universitätsspital Basel, Basel, Switzerland. 15 Radiation Oncology, University Hospital Zurich, University of Zurich, Zürich, Switzerland. 16 Radiation Oncology, Humanitas Clinical and Research Hospital, IRCSS, Radiotherapy and Radiosurgery Department, Rozzano, Switzerland. 17 Radiation Oncology, Health Research Institute, University Hospital La Princesa, Madrid, Spain. 18 Radiation Oncology, Complejo Hospitalario de Navarra, Navarra, Spain. 19 Radiation Oncology, Instituto Oncólogico Clinica Universitaria IMQ, Bilbao, Spain. 20 Radiation Oncology, University Hospital Quironsalud, Madrid, Spain and Universidad Europea de Madrid, Madrid, Spain. 21 Radiation Oncology, Napoli Istituto Nazionale Tumori IRCCS Fondazione Pascale, Napoli, Switzerland. 22 Radiation Oncology, AZ St-Lucas Ghent, Ghent, Belgium. 23 Medical Oncology, Geneva University Hospital (previous institution), Geneva, Switzerland. 24 Radiation Oncology, Ghent University Hospital, Ghent, Belgium. 25 Department of Human structure and repair, Ghent University, Ghent, Belgium. 26 Department of Applied Mathematics, Computer Science and Statistics, Ghent University, Ghent, Belgium Purpose/Objective Pelvic nodal recurrences are being increasingly diagnosed in prostate cancer (PCa) patients with the introduction of new molecular imaging techniques, like PSMA PET-CT. There are no specific treatment recommendations for patients with these recurrences and different locoregional treatment approaches are currently being used. Here we report the primary endpoint, metastasis-free survival in addition to the secondary endpoints of metastasis directed therapy (MDT) versus elective nodal pelvic radiotherapy (ENRT). Material/Methods STORM – PEACE V is an international, phase II, open-label, randomised, superiority trial conducted in 6 countries. Patients diagnosed with PET-detected pelvic nodal oligorecurrence (≤5 nodes) following radical local treatment for PCa, were randomized in a 1:1 ratio between arm A: MDT, by means of salvage lymph node dissection or SBRT (3x10Gy) with 6 months of androgen deprivation therapy (ADT), or arm B: ENRT (25x1.8Gy) with MDT (SIB boost) and 6 months of ADT. The primary endpoint is metastasis-free survival (MFS) and alpha set at 0.20 with the following secondary endpoints: biochemical relapse-free survival (bRFS), locoregional relapse free survival (lrRFS), ADT-free survival (ADT-FS), and late toxicity within 48 months of treatment using the Common Terminology Criteria for Adverse Events (CTCAE) v4.0 scale. All analysis were done for the intent-to treat population. This study is registered on ClinicalTrials.gov (Identifier: NCT03569241). Results Between June 2018 and April 2021, 196 patients were randomly assigned to MDT (n=99) or ENRT (n=97) , with 190 evaluable patients (MDT:93 and ENRT: 97). PET-tracer was choline in 32 (17%) patients and PSMA in 157 (83%) patients. Median follow-up for the entire group is 50 months with a median time to biochemical failure was 30 months for MDT versus 58 months for ENRT (p=0.014). ENRT improved MFS compared to MDT (HR 0.62, 80% CI 0.44-0.86; p=0.06), resulting in a 4-year MFS rate of 63% for MDT versus 76% for ENRT. ENRT also