ESTRO 2025 - Abstract Book

S1650

Clinical – äediatric tumours

ESTRO 2025

Conclusion: Pediatric patients with localized and oligometastatic pelvic Ewing's sarcoma exhibit comparably favorable survival outcomes, whereas the presence of widespread metastatic disease significantly compromises prognosis. These findings suggest that oligometastatic disease aligns more closely with localized disease within the spectrum of Ewing's sarcoma, highlighting the importance of implementing aggressive local therapeutic strategies targeting both the primary tumor and metastatic sites.

Keywords: ewing sarcoma, oligometastatic, radiotherapy

3894

Digital Poster Preliminary clinical experience of proton therapy in national pediatric rhabdomyosarcoma: clinical outcomes and toxicity profile Sofia Paola Bianchi 1 , Petra Mozes 1 , Ulrike Mock 1 , Matthias Stephan Moll 1 , Robert Savary Malyapa 1 , Piero Fossati 1,2 , Leonie Brodbek 3 , Antonio Carlino 3 , Eugen Hug 1 , Carola Luetgendorf-caucig 1 1 Department of Radiation Oncology, MedAustron Center for Ion Therapy, Wiener Neustadt, Austria. 2 Department of Basic and Translational Oncology and Hematology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria. 3 Department of Medical Physics, MedAustron Center for Ion Therapy, Wiener Neustadt, Austria Purpose/Objective: Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. Treatment of RMS in infants remains challenging, often associated with acute and long-term toxicities. Proton therapy (PT) has the potential to reduce integral dose and exposure to organs at risk. We report our experience with PT in the management of RMS in infants. Material/Methods: Between 2017 and 2024, 18 Austrian children (female 7, male 12) with the mean age of 3 years (range:1-15) diagnosed with RMS received pencil beam scanning PT at MedAustron. Fifteen patients received treatment according to the CWS guidelines, while the remaining four were treated according to the FarRMS protocol (two enrolled in the protocol, and two treated per protocol). Follow-up (FU) included imaging (CT and MRI) and clinical evaluation. Acute and late toxicities were assessed using the Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Local control (LC), progression-free survival (PFS), and overall survival (OS) were calculated using Kaplan-Meier survival analysis.