Gamma Knife Stereotactic Radiosurgery in Combination with Bevacizumab for Recurrent Glioblastoma.

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.

Magnetic resonance imaging appearance and changes on intracavitary Gliadel wafer placement: A pilot study.

AIM: To investigate changes on magnetic resonance imaging (MRI) which occur with intracavitary Gliadel wafer placement in patients with glioblastoma multiforme (GBM). METHODS: This retrospective Health Insurance Portability and Accountability Act-compliant study was approved by the institutional review board, with a waiver of informed consent. A total of eight patients aged 29-67 years with GBM underwent Gliadel wafer placement. T2-weighted/FLAIR images and post-contrast T1-weighted images both before and after wafer placement were retrospectively reviewed in consensus to determine changes in the following parameters: appearance of the pericavitary tissue, pattern of tumor recurrence or progression and appearance of the Gliadel wafer itself. RESULTS: Five out of the eight patients had a progressive increase in enhancement and pericavitary T2/ FLAIR hyperintensity within the first 2 mo and a subsequent decrease in these MRI findings. None of these patients had tumor recurrence within the first 6 mo. Three out of the eight patients demonstrated a progressive increase in enhancement and pericavitary T2 hyperintensity, which continued after the first 6 mo, and were subsequently diagnosed with true tumor progression. There was no increase in distant/nonlocal tumor recurrence. The Gliadel wafer appearance changed over time. CONCLUSION: Pseudoprogression is common after intracavitary Gliadel wafer placement and thus care should be taken before diagnosing tumor progression or recurrence within the first 2 mo.