Background: Prior retrospective and prospective studies suggest improved survival with the use of stereotactic radiosurgery (SRS) and bevacizumab in the treatment of limited-volume glioblastoma (GBM) recurrences.
Methods: We retrospectively reviewed our experience with gamma knife SRS in combination with bevacizumab for the treatment of focal GBM recurrence during 2009-2015. Outcomes include overall survival, progression free survival (PFS), and radiation-related adverse events. Kaplan-Meier methods and multivariable Cox proportional hazards models were performed for survival analysis.
Results: Within a median of 13.7 months after diagnosis, a total of 45 patients with GBM underwent gamma knife SRS and bevacizumab treatment. Median age was 57 years (range: 20-78 years) and 63.3% were women. The median Karnofsky Performance Score (KPS) at recurrence was 80 (range: 40-100). Sixty-four percent of patients had single radiosurgery target (range: 1-4) and median target volume and margin dose were 2.2 cm3 (range: 0.1-25.2 cm3) and 17.0 gray (Gy) (range: 13-24 Gy), respectively. Median PFS and overall survival were 9.3, 31.0 months following diagnosis, and 5.2, 13.3 months after SRS, respectively. Factors associated with poor outcomes were KPS ≤70, SRS dose <18 Gy, and use of <2 chemotherapy agents prior to SRS. No radiation-related adverse events occurred.
Conclusions: SRS in combination with bevacizumab can be safely used to treat focal GBM recurrence. KPS, radiation dose, and multi-agent chemotherapy usage prior to SRS demonstrated significant impact on PFS. Bevacizumab may provide clinically relevant radioprotection.
Keywords: Bevacizumab; Gamma knife; Radiosurgery; Recurrent glioblastoma; Stereotactic radiosurgery.
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