Long-Term Outcomes and Quality of Life of Children With Intracranial Ependymoma Treated With Pencil Beam Scanning Proton Therapy.

Abstract

Background: Ependymoma is a common brain tumor in children and adolescents. Adjuvant radiation therapy improves prognosis but carries potential toxicity risks, particularly for young patients. Proton therapy (PT) offers better conformal treatments and reduces dose exposure compared to traditional photon radiotherapy.

Procedure: This study retrospectively analyzed long-term outcomes of children treated with pencil beam scanning (PBS) PT for intracranial ependymomas (EPs) at the Paul Scherrer Institute (PSI) between 2004 and 2022.

Results: We identified 119 children, with most having infra-tentorial tumors (70.6%) and anaplastic ependymomas (82.4%). The median PT dose was 59.4 Gy_RBE delivered in 1.8 Gy_RBE/fraction. Follow-up at 5 years showed 70.4% local control, 63.5% progression-free survival (PFS), and 82.2% overall survival (OS). OS was better with upfront than relapse treatment (83% vs. 69.8%; p = 0.024), and complete resection improved both LC (74% vs. 65.1%; p = 0.033) and PFS (67.5% vs. 57.1%; p = 0.049) compared to subtotal resection. No hearing loss was observed with cochlea D_max not exceeding 48 Gy_RBE (10.5% vs. 0%; p = 0.0097), whereas the risk of hormone deficiency was significantly increased with pituitary D_mean above 38 Gy_RBE (33.3% vs. 6.0%; p = 0.00007). Most patients (72.3%) had no late toxicity. Four secondary brain malignancies (3.4%) occurred within a median of 9.3 years after PT (range: 3.7-15). Quality of life 5 years after PT was good in older (>4 years) patients, though proxy-rated social functioning was poorer than the norm group.

Conclusion: Intracranial PBS-PT offers excellent tumor control and low late toxicity, and revealed good overall quality of life in children with ependymoma, both by proxy- and self-assessment.