A Single-arm Phase II Non-inferiority Clinical Study of Limited Target Volume Radiotherapy After Glioblastoma Surgery

Research on radiotherapy target volumes for glioblastoma is increasingly focused on exploring more limited yet effective irradiation fields, aiming to achieve local control while minimizing acute and long-term neurotoxicity. Previous retrospective analysis by investigators revealed that local recurrences of glioblastoma are predominantly confined to a narrow margin around the original lesion: 98.3% of recurrences occurred within 0.5 cm of the original T2-FLAIR abnormality, 94.8% within 1 cm of the original T1-enhanced region. These findings have been cited in the ESTRO-EANO treatment guidelines. Building on this evidence, investigators plan to conduct a single-arm, phase II clinical trial to systematically evaluate the efficacy and safety of a 1 cm radiotherapy target volume in post-operative glioblastoma patients.Eligible patients with glioblastoma who have undergone surgical resection will be selected to receive limited-field radiotherapy. The target volume will be defined based on the postoperative MRI enhancing lesion: a 1 cm margin will be added to form the clinical target volume (CTV), followed by a further 0.3 cm margin to create the planning target volume (PTV). A total dose of 60 Gy will be delivered in 30 fractions (2 Gy per fraction, 5 fractions per week). Concurrent and adjuvant chemotherapy will be administered per standard guidelines. The primary efficacy endpoints are the 6-month progression-free survival rate and the incidence of symptomatic radiation-induced brain necrosis of grade 3 or higher. Secondary endpoints include overall survival, patterns of recurrence, neurocognitive function, and quality of life.