Changing prognosis of glioblastoma multiforme (GBM) in the 21st century: The influence of age and regional income.

Abstract

6089 Background: The addition of concurrent/adjuvant temozolomide (TMZ) to post-operative radiation therapy (RT) has been shown to improve overall survival (OS) of GBM patients in a randomized trial testing the benefit of this treatment in patients <70 years. It is unknown if this benefit has been reflected at the population-based level. We therefore performed a population-based survival analysis of newly diagnosed GBM patients covering the period before and after the introduction of TMZ. We further analyzed the impact of mean regional income on any improvements in OS during this time period. Methods: Survival statistics and pertinent clinical and demographic variables were extracted from the Survival, Epidemiology and End Results (SEER) Database for GBM patients diagnosed from 2001-2007. Patients were divided into income quartiles based on mean household income in their county of residence. Survival was analyzed using the Kaplan-Meier method. A multivariate analysis (MVA) was performed to determine independent prognostic factors associated with OS using proportional hazard models. A p-value <0.05 was considered statistically significant. Results: We identified 13,303 adult patients diagnosed with a GBM from 2001-2007. One and 2-year estimated OS rates were 37% and 14% respectively. Favorable prognostic variables identified on MVA included age <70 years, use of RT, gross total resection (GTR), later year of diagnosis, and residence in a high-income district (HI) (p <0.001). From 2001-2007, the median survival time increased from 7 to 9 months for the entire population. One-year survival rate increased from 29% to 39%. Outcomes in patients >70 years did not improve over this period, even amongst patients who had GTR and RT. Over the study period, the absolute disparity in one-year survival between economically poor-and-affluent areas increased from 6.6% to 10.1%. Conclusions: Prognosis of GBM patients has continuously improved from 2001-2007. This improvement has been confined to patients <70 years and has been most prominent amongst patients living in HI districts. Future efforts should be made to identify and mitigate factors contributing to the widening economic disparities gap.