Introduction: There has been promising retrospective data, which suggests a survival benefit with the use radiosurgery and bevacizumab in the treatment of glioblastoma (GBM) recurrences. The existing data is derived from small cohorts, which has limited analysis of the concomitant therapies efficacy.

Methods: We retrospectively reviewed our experience with GK in combination with bevacizumab for the treatment of focally recurrent glioblastoma (GBM) from 2009 – 2015. Statistical analysis was performed using a Cox regression model. Progression-free and overall survival (OS) were estimated using the Kaplan–Meier method.

Results: Within a median of 13.7 months after initial diagnosis, a total of 45 GBM patients underwent initial GK in combination with bevacizumab treatment. Median age was 57 years and 63.3% of subjects were female. The median KPS at recurrence was 80 (range: 40 – 100). Sixty-four percent of patients had one treatment target (range: 1 – 4) and median target volume and dosage were 2.2 cm3 (range: 0.1 – 25.2 cm3) and 17.0 Gy (range: 13 – 24 Gy), respectively. Median PFS and OS were 9.3 and 31 months following diagnosis, and 5.2 and 13.3 months after initial radiosurgery, respectively. Factors associated with poor outcomes in this study are use of > 3 chemotherapies and > 3 radiosurgical targets at initial recurrence. No adverse events of radiation were identified in our cohort.

Conclusions: Stereotactic radiosurgery and bevacizumab can be effectively used to treat focal recurrences of GBM. Increased number of chemotherapy agents and radiosurgical targets correlate with poorer outcomes, likely reflective of a larger tumor burden. Concurrent bevacizumab use resulted in a low incidence of radionecrosis and toxicity compared to published studies, and confers clinically relevant radioprotection in the setting of SRS re-irradiation.

Patient Care: Our study supports data from prior smaller series that suggest the combined use of bevacizumab and radiosurgery may improve survival for those with focal GBM recurrences. In addition, out data shows that it is a well-tolerated treatment approach.

Learning Objectives: 1. Understand the natural history of recurrent glioblastoma. 2. Describe the mechanism of radiation injury and bevacizumab's role in suppressing its manifestations. 3. Understand the role of radiosurgery and bevacizumab in focally recurrent glioblastoma.

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