Study of Adaptive Radiotherapy for High‐Grade Glioma Based on Interfraction MRI

BACKGROUND: Currently, there is no clear guidance on the appropriate population or timing for adaptive radiotherapy (ART) in high-grade glioma (HGG) patients. This study aims to provide individualized ART for HGG patients. METHODS: Participants received standard "radiotherapy combined with temozolomide" and underwent MRI before radiotherapy (FX0), after fraction 10 (FX10), and after fraction 20 (FX20). The primary endpoint was anatomical and dosimetric changes in targets and organs at risk (OARs). RESULTS: Among the 73 eligible patients, significant anatomical changes occurred during chemoradiotherapy, particularly at FX10. ART significantly improved target dose coverage and reduced OAR doses compared with projection plans. Univariable and multivariable logistic regression analysis identified Relative volume change (Vrel)_CTV ≥ 7% as an independent risk factor for dosimetric changes, with IDH wild-type and tumor diameters < 5 cm as independent risk factors. Median follow-up was 12 months; median progression-free survival (PFS) was 18 months. D_migration_max_CTV ≥ 8.5 mm was associated with worse PFS. CONCLUSIONS: Implementing ART after FX10 is recommended. HGG patients with wild-type IDH and tumor diameters < 5 cm should be prioritized for ART. Patients with D_migration_max_CTV ≥ 8.5 mm require more intensive treatment. TRIAL REGISTRATION: The trial was prospectively registered (ClinicalTrials.gov, NCT06201351).