Background: Glioblastoma (GBM) is an aggressive disease with limited therapeutic options. While bevacizumab was approved in 2009 for the treatment of patients with recurrent GBM, its impact on overall survival (OS) remains unclear. This study utilizes population-based cancer registry data to compare OS of patients diagnosed with GBM before versus after bevacizumab approval. Methods: Adult patients diagnosed with GBM were identified in the SEER database and divided into 2 cohorts: patients diagnosed in 2006-2008 (Pre-Bevacizumab Cohort, n=6,120) and patients diagnosed in 2010-2012 (Post-Bevacizumab Cohort, n=6,753). All patients were included irrespective of the treatments received. OS was assessed from diagnosis (dx) date up to 3-years post-dx. Results: Among 12,873 patients with GBM, the median age was 62 years, 41% were females, 31% underwent gross total resection, and 75% received radiation therapy. OS rates at 1 and 2 years post-dx were significantly higher for the Post-Bevacizumab Cohort versus the Pre-Bevacizumab Cohort (44 vs 40% and 21 vs 19%, p <.01, Table). After adjusting for potential confounders, the hazard of death remained significantly lower in the Post-Bevacizumab Cohort (hazard ratio [HR] 0.91, p <.01, Table). Survival was stable within the 2006-2008 period (median survival = 9 months for all years), but increased after year 2009 (median survival = 10 and 11 months for years 2010-2011 and 2012, respectively). Conclusions: Based on this large population-based study, the survival following glioblastoma diagnosis improved 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 may indicate a potential benefit of bevacizumab on recurrent GBM survival.

* From Kaplan-Meier analyses. † HRs estimated from Cox regression models adjusted for age, gender, race, radiation therapy, and surgery type. A HR<1 indicates the Post-Bevacizumab Cohort had longer survival.