Proton therapy for adult-type IDH-mutated glioma: Proglio-1, a multicenter retrospective study
This multicenter retrospective study, conducted under the French PROGLIO-1 project, evaluated the clinical outcomes and toxicity profile of proton therapy (PT) in patients with adult-type IDH-mutated glioma. Given the typically long survival and treatment-related neurocognitive risks in this population, PT’s dose conformity and normal tissue sparing offer potential advantages over conventional photon radiotherapy. Data were collected from 11 French proton therapy centers and included 155 adult patients treated between 2016 and 2023. The median follow-up was 42 months. Most patients (76%) had grade 2 tumors, while 24% had grade 3 disease, according to WHO 2021 classification. The median delivered dose was 54 Gy (RBE) in 30 fractions.
Results showed excellent tumor control, with a 3-year progression-free survival (PFS) rate of 84% and overall survival (OS) of 94%. Local control remained high across all subgroups, including both astrocytoma and oligodendroglioma histologies. Acute toxicity was mild, with grade ≥2 adverse events observed in less than 10% of patients, primarily fatigue and headache. Late toxicities, including radionecrosis and cognitive impairment, were rare (<3%). Importantly, PT allowed reduced dose exposure to critical brain structures such as the hippocampi, temporal lobes, and optic pathways, suggesting a potential long-term neuroprotective effect.
These findings demonstrate that proton therapy provides effective tumor control with minimal toxicity in IDH-mutated glioma, aligning with the goal of preserving neurocognitive function in patients with favorable prognosis. The study concludes that PT is a safe and efficient modality for this molecularly defined glioma subgroup and supports its inclusion in future prospective trials to confirm benefits in quality of life and functional outcomes compared with advanced photon techniques.
Radiation Oncology Volume 20, Article number: 124 (2025) Accepted 23 July 2025 – Published 05 August 2025- DOI: https://doi.org/10.1186/s13014-025-02702-y
