ESTRO 2025 - Abstract Book

S1654

Clinical – äediatric tumours

ESTRO 2025

We report in this retrospective serie the experience of the first Spanish proton therapy center using a single room compact system in treatment of medulloblastoma.

Material/Methods: Quiron Proton Therapy Center (CPT) opened in Madrid in December 2019 and is treating patients referring from whole Spain. We reviewed all patients treated at CPT for a medulloblastoma from January 2020 to May 2024 at CPT with a Proteus®ONE system from IBA. A descriptive analysis for toxicities and local control was performed, and we analysed overall survival (OS) and disease-free survival (DFS) using Kaplan-Meier survival analysis. Results: 50 patients with a median age of 8 (3 – 47) years were treated. 42 (84%) patients were children and 8 (16%) young adults. 50% were high risk and 50% standard risk. All patients with high risk disease received a craniospinal irradiation of 36 GyRBE followed by a posterior fossa boost at a total dose of 54 - 55.8 GyRBE. 22 (88%) patients with standard risk medulloblastoma received a craniospinal irradiation of 23.4 GyRBE, 2 (8%) 36 GyRBE and 1 (4%) 18 GyRBE and a posterior fossa boost up to a total dose of 54 GyRBE. All patients received adjuvant chemotherapy. Grade 3 hematologic toxicity was observed in 3 patients (6%). None patients presented grade > 3 toxicity. 6 (12%) patients had neurocognitive impairment, 3 (6%) pituitary dysfunction, 3 (6%) hearing loss and 1 (2%) visual deficit. At a median follow of 13 (5 – 44) months, loco-regional control rate was 86.7%. OS at 1 and 3 years were 96% and 89%; and DFS 89% and 82%. Conclusion: Proton therapy for medulloblastoma using a compact system is a safe and feasible with encouraging result in term of tumour control and low acute toxicity. Benefit in term of late effects need a longer follow-up to be evaluated. Mini-Oral evaluation of amygdala dose and emotion regulation disorders after brain irradiation in paediatric tumours Claire Dossun 1 , Anne Laprie 2 , Georges Noël 3 , Eloise Baudou 4 , Anne Ducassou 2 , Fatima Tensaouti 5 , Leonor Chaltiel 6 1 Radiotherapy, Institut de cancérologie Strasbourg Europe, Strasbourg, France. 2 Radiotherapy, Institut Claudius Regaud, Institut Universitaire du Cancer de Toulouse Oncopole, Toulouse, France. 3 Radiotherapy, Institut de cancérologie Strasbourg Europe, Faculté de médecine Université de Strasbourg, laboratoire de radiobiologie iCUBE IMIS (Imagerie multimodale Intégrative en Santé), Strasbourg, France. 4 Pediatric neurology, Hôpital des Enfants Purpan, Toulouse, France. 5 Research department, Oncopole Claudius Regaud, Institut Universitaire du Cancer de Toulouse and 2 Toulouse NeuroImaging Center, Université de Toulouse, Inserm, Toulouse, France. 6 Research department, Institut Claudius Regaud, Toulouse, France Purpose/Objective: Radiotherapy (RT) is the primary indication for brain tumors treatment in children, with well-established dose constraints for visual, auditory, and endocrine organs. However, the cerebral amygdala, essential for emotional regulation, is not yet delineated in clinical practice. This study aims to evaluate whether there is a correlation between the dose delivered to the amygdala and the onset of emotional regulation disorders in patients who have undergone RT for brain tumors. Keywords: protons, medulloblastoma, craniospinal 4295

Material/Methods: This bi-centric prospective study was approved by the local ethics committee. Seventeen children were included.