Safety and Efficacy of Hypofractionated Stereotactic Radiosurgery for High-Grade Gliomas at First Recurrence: A Single-Center Experience

Background: The optimal treatment for recurrent high-grade gliomas (rHGG) remains uncertain. This study aimed to investigate the efficacy and safety of CyberKnife radiosurgery as a salvage treatment for in field recurrence of high-grade gliomas at first time. Methods: Between January 2016 and October 2019, seventy patients with rHGG undergone CyberKnife radiosurgery were retrospectively analyzed. The primary endpoint was overall survival (OS), and secondary endpoints included both progression-free survival (PFS) and adverse events which was according to Common Toxicity Criteria Adverse Events (CTCAE) version 5. The prognostic value of key clinical features (age, performance status, planning target volume, dose, use of bevacizumab) were evaluated. Results: A total of 70 patients were included in the study. Forty patients were male and 30 were female. Forty-nine had an initial diagnosis of glioblastoma (GBM), and the rest (21) were confirmed to be WHO grade 3 gliomas. The median planning target volume (PTV) was 16.68 cm3 (0.81 – 121.96 cm3). The median prescribed dose was 24 Gy (12-30 Gy) in 4 fractions (2-6 fractions). Median baseline of Karnofsky Performance Status (KPS) is 70 (40 - 90). With a median follow-up of 12.1 months, the median overall survival after salvage treatment was 17.6 months (19.5 and 14.6 months for grade 3 and 4 gliomas respectively; p = .039). No grade 3 or higher toxicities was recorded. Multivariate analysis showed that concurrent bevacizumab with radiosurgery and KPS>70 were favorable prognostic factors for grade 4 patients with HGG. Conclusions: Salvage CyberKnife radiosurgery showed a favorable outcome and acceptable toxicity for rHGG. A prospective phase II study (NCT04197492) is ongoing to further investigate the value of hypofractionated stereotactic radiosurgery (HSRS) in rHGG.