Patterns of care in primary brain tumour Reirradiation: A survey by the ESTRO CNS focus Group.

BACKGROUND

Reirradiation is increasingly considered for patients with recurrent primary brain tumours, yet clinical practices vary significantly due to limited evidence and a lack of standardized guidelines. This survey aimed to map European practice patterns in brain tumour reirradiation.

METHODS

A 23-item web-based survey was developed by the ESTRO CNS Focus Group to assess institutional characteristics, clinical decision-making, and technical aspects of reirradiation. Distributed via email and social media, the survey collected responses between June-July 2025. Descriptive statistics were applied.

RESULTS

Eighty responses from 28 European countries were analysed. High-grade gliomas were the most frequently reirradiated tumours (>80 %), followed by meningioma (56 %, low-grade glioma (49 %), and ependymoma (44 %). Conventional photon radiotherapy (RT) was the predominant technique across all tumour types, with varying use of hypofractionation, stereotactic RT, and proton therapy. Target volume definition and margin size varied by histology, with larger margins and inclusion of edema/cavities more frequent in gliomas. MRI-CT fusion was standard for planning. Concurrent systemic treatment was used mainly in high-grade gliomas. Organ at risk dose recovery and cumulative constraints were commonly considered, but threshold values and recovery models differed. Main barriers included fear of toxicities, including radiation necrosis and limited evidence.

CONCLUSION

This survey reveals high heterogeneity in brain tumour reirradiation practices across Europe, especially regarding dose, technique, and target definition. Despite shared principles, consensus is lacking for rarer tumour types. These findings underscore the need for harmonized guidelines and prospective data to optimize patient care.