Impact of stereotactic radiosurgery on first recurrence of glioblastoma

Abstract

Background and Aim: The benefit of stereotactic radiosurgery (SRS) in recurrent glioblastoma multiforme (GBM) remains unclear, partly due to disease heterogeneity. Subventricular zone (SVZ) invasion is a prognostic factor for primary GBM, but whether SVZ involvement is also prognostic in recurrent GBM treated with SRS is unknown. Here, we aimed to determine prognostic factors after first GBM recurrence. Materials and Methods: Thirty-nine consecutive patients with a first recurrence of glioblastoma treated at the Gamma Knife Center, Warsaw, Poland and the Franciszek Lukaszczyk Oncology Center, Bydgoszcz, Poland, between 2012 and 2016 were retrospectively reviewed. Magnetic resonance images were reviewed according to SVZ invasion by primary tumors and at the time of recurrence. Outcomes were evaluated using univariable and multivariable analyses. The study protocol was approved by the Ludwik Rydygier Collegium Medicum of Nicolas Copernicus University Institutional Review Board (approved No. KB 494/2018) on June 19, 2018. Results: SRS was the only prognostic factor for overall survival after recurrence in multivariable analysis. The median overall survival after the first recurrence was 18 months in the SRS group versus 6.5 months in the non-SRS group (P = 0.02). Survival after the first recurrence treated with SRS was shorter when recurrences were localized to the SVZ. Conclusion: SRS appears to be an effective salvage modality for small recurrent GBMs. Although SVZ-positive tumors have a worse prognosis, these tumors may benefit from SRS.