Overall survival in patients with glioblastoma before and after bevacizumab approval

Abstract

Objective: Glioblastoma (GBM) is an aggressive disease with limited therapeutic options. While bevacizumab was approved in 2009 for the treatment of patients with progressive GBM, its impact on overall survival (OS) remains unclear. Using US population-based cancer registry data (SEER), this study compared OS of patients diagnosed with GBM before and after bevacizumab approval.

Methods: Adult patients from SEER with a GBM diagnosis were divided into two cohorts: patients diagnosed in 2006-2008 (pre-bevacizumab cohort, n = 6,120) and patients diagnosed in 2010-2012 (post-bevacizumab cohort, n = 6,753). Patients were included irrespective of the treatments received. OS post-diagnosis was compared between the study cohorts utilizing Kaplan-Meier analyses and multivariate Cox proportional hazards regression.

Results: Among 12,873 patients with GBM, the median age was 62 years, 41% were women, 31% underwent gross total resection, and 75% received radiation therapy. Survival was stable within the 2006-2008 period (median survival = 9 months for each year), but increased after year 2009 (median survival = 10 and 11 months for years 2010/2011 and 2012, respectively). The adjusted hazard of death was significantly lower in the post-bevacizumab approval cohort (hazard ratio = 0.91, p < .01).

Conclusions: The results of this large population-based study suggested an improvement in OS among patients with a GBM diagnosis in 2010-2012 compared to 2006-2008. While the cause of this improvement cannot be proven in a retrospective analysis, the timing of the survival increase coincides with the approval of bevacizumab for the treatment of patients with progressive GBM, indicating a possible benefit of bevacizumab in this population.

Keywords: Glioblastoma; bevacizumab; cancer registry; pre–post design; survival.