RTRB-04STEREOTACTIC RADIOSURGERY FOR RECURRENT HIGH-GRADE GLIOMAS: PATIENT SELECTION AND THE ROLE OF BEVACIZUMAB

PURPOSE: Despite favorable outcomes in retrospective reports, the role of stereotactic radiosurgery (SRS) with and without bevacizumab (BVZ) for the treatment of recurrent high-grade gliomas (HGG) is controversial. To explore factors predictive of outcome with SRS, we examined our experience of SRS with and without BVZ for recurrent HGG. METHODS: 273 patients with 308 lesions were treated at our institution with SRS for recurrent HGG from 2005-2010. Data collected at the time of SRS included clinical descriptors, demographics, radiation-specific metrics, and use of BVZ before (after initial diagnosis but ≥3 weeks preceding SRS), concurrent with (u003c3 weeks preceding SRS) and after SRS. Progression-free (PFS-SRS) and overall survival from the time of SRS (OS-SRS) were calculated using the Kaplan-Meier method. Multivariable analyses (MVA) were performed using the Cox model to identify factors predictive of outcomes. RESULTS: Histology was glioblastoma multiforme (GBM) in 210 patients, anaplastic astrocytoma (AA) in 43, and anaplastic oligodendroglioma (AO) in 20. BVZ was used before, concurrent with, and following SRS in 74.0%, 79.5%, and 79.9% of patients, respectively. Median PFS-SRS rates were 4, 5.8, and 8 months for GBM, AA and AO, respectively (p = 0.0005). Corresponding OS-SRS rates were 8.7, 9.5, and 26.2 months, respectively (p = 0.0015). MVA identified GBM histology, BVZ before SRS, and lower KPS as significantly associated with worse PFS-SRS and OS-SRS. Additionally, a longer progression-free interval predicted better OS-SRS. CONCLUSIONS: Rates of PFS-SRS and OS-SRS compare favorably with published data. As expected, histology, higher KPS, and longer progression-free interval since diagnosis were associated with longer survival. Patients not treated with BVZ at initial diagnosis and/or more than 3 weeks prior to SRS exhibit improved outcomes following SRS. One hypothesis is that BVZ masks the full extent of disease visualized on treatment-planning MRI, limiting the efficacy of SRS. Further analyses and prospective data are needed.