Retrospective Review of Factors Associated with Survival in Patients Treated with Gamma Knife for Recurrent Glioblastoma.

Abstract

Listen

Translate article

Stereotactic radiosurgery (SRS) has been utilized to offer patients a non-surgical option for glioblastoma recurrence. Prior studies indicate that dose >15 Gy has a positive impact on patient survival. We hypothesized that both treatment dose and the volume of recurrence would correlate with patient outcome in a retrospective review of a single institutional experience. This was a single institution retrospective review of all patients treated with radiosurgery for glioblastoma recurrence from 2009-2018. All patients were treated with 59.4-60 Gy in 1.8-2.0 Gy fractions with concurrent temozolamide at the time of their initial diagnosis. Overall survival (OS) was estimated using Kaplan-Meier survival curves and examined using multivariate cox proportional hazard regression models (MVA). Data management and decision management software was used for analyses. Fifty-five patients were eligible for analysis with a median follow-up of 18.2 months. Median age was 55 years (range: 16-82 years), and 35 patients (64%) were male. Fifty-two (95%) underwent either gross total or subtotal resection at the time of initial treatment. Fourteen patients (25%) underwent a second surgical resection prior to GK. Six patients (11%) had already received a repeat course of external beam radiation for a previous recurrence. Median dose was 15 Gy (range: 7-25Gy). Dose >15 Gy was associated with a trend towards improved survival (p=0.058). There was no association between dose and volume of recurrence (R2=0.01). On MVA, dose >15 Gy (p=0.02) and time >20.2 months from primary therapy to GK (p=0.03) were associated with improved OS. Age, RPA group, and volume of recurrence were not significant predictors of outcome. Findings are consistent with previous literature supporting dose >15 Gy and longer freedom from recurrence as features predictive of OS for patients with recurrent glioblastoma. Because volume of recurrence was not associated with delivered dose or patient survival, these results suggest dose >15 Gy should be considered regardless of volume. Further studies are needed to characterize toxicity.