S1014
Clinical – Paediatric tumours
ESTRO 2026
However, due to the risk of late adverse events (AEs), nowadays radiotherapy is typically deferred for salvaging after failure. In case of radiotherapy, proton beam therapy (PT) is increasingly used to limit burden to the normal tissue. We evaluated our results regarding treatment outcomes in pediatric patients with low-grade glioma treated with protons in our institution. Material/Methods: All children with a low-grade glioma enrolled into the prospective registry study “KiProReg” (DRKS00005363) receiving PT were assessable. Patient, tumor and treatment characteristics were recorded and analysed. Acute and late AEs were documented and scored according to CTCAE v4.0 and 5.0, respectively. Kaplan- Meier estimates were calculated for progression free survival (PFS), overall survival (OS) and local control (LC) rates. Patterns of failure were investigated according to local, distant or combined events. Results: The analysis included data from 78 patients (31 males and 47 females). Median age of patients was 11.4 years (range, 1.2-17.9). In 44 patients, pilocytic astrocytomas were confirmed. In 11 patients, dissemination of disease was already present at the time of PT (14.1%). In only two patients, gross total or near total resection was achieved during the course of disease. Chemotherapy was given previously in 22 patients and concurrently in three patients. Three patients had already undergone previous radiotherapy. Median total dose of last PT course was 54 Gy(RBE) (range, 30.6-55.8 Gy(RBE)) with a median fraction dose of 1.8 Gy(RBE) (range, 1.6-2.0 Gy(RBE)). Median follow-up from 1st diagnosis to last contact was 4.9 years (range, 0.2-16.5). At last contact, 18 patients had experienced local (n=16) or distant (n=2) failure, 11 patients (14.3%) were deceased. Estimated OS, PFS and LC rates were 92%, 58%, and 65%, respectively (Figure 1 and 2). Three years after PT, performance status and AE rates were typically improved when compared with baseline. However, higher-grade visual AEs, already present in 23% of patients at baseline, persisted in a subset of patients up to year 3. One patient undergoing PT after multiple recurrences experienced symptomatic neurovasculopathy and died following surgical intervention.
diagnosis. Total macroscopic resection was successfully performed in 44 (81%) cases. Finally, 35 (65%) were classified as standard risk and 19 (35%) as high risk. All patients received radiotherapy; 32 (59%) with photons and 14 (41%) with protons, with craniospinal doses ranging between 23.4–39.6Gy. 31 (57%) patients received adjuvant chemotherapy (Packer, St Jude’s, and COG/PNET protocols, or platinum-vincristine-alkylator combinations). Among high-risk patients, 14 (74%) received adjuvant chemotherapy. In the standard-risk group, nine (26%) received 23.4Gy plus chemotherapy, eight (23%) received 36Gy plus chemotherapy, and 18 (51%) received 35.04–39.6Gy without chemotherapy. After a median follow up of 40 months, five (9%) patients relapsed, and three (6%) died. Recurrences included three local and two distant events. The 3-year RFS and OS for the entire cohort were 88% and 95%, respectively. In the standard-risk subgroup, 3-year RFS and OS were 89% and 96%; in the high-risk subgroup, 87% and 94%. Among standard-risk patients, the 3- year RFS and OS were 87% and 93% for patients who received chemotherapy, and 92% and 100% in those without chemotherapy (RFS p=.7497; OS p=.9870). Conclusion: This large single-centre series shows excellent oncological outcomes in adults with medulloblastoma, including standard-risk patients treated without adjuvant chemotherapy. Prospective multi-centre studies are needed to validate these findings. Keywords: medulloblastoma, protons, photons Proton beam therapy for low-grade gliomas of childhood – results from the prospective registry study “KiProReg” Beate Timmermann 1,2 , Kristy Köhler 1 , Julien Merta 1 , Sandija Plaude 1 , Dalia Ahmad Khalil 1 , Sarah Peters 1 , Sied Kebir 3,2 , Stephan Tippelt 4 1 Department of Particle Therapy, West German Proton Therapy Centre Essen (WPE), West German Cancer Poster Discussion 2929 Center (WTZ), University Medicine Essen, Essen, Germany. 2 German Cancer Consortium (DKTK) , Essen/Düsseldorf, University Medicine Essen, Essen, Germany. 3 Department of Neurology and Center for Translational Neuro- and Behavioral Sciences (C- TNBS), Division of Clinical Neuro-Oncology, University Medicine Essen, University Duisburg-Essen, Essen, Germany. 4 Department of Pediatrics III, Pediatric Oncology and Hematology, University Hospital Essen, Essen, Germany Purpose/Objective: Radiotherapy is the most effective non-surgical treatment for low-grade gliomas of childhood.
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