Limited survival benefit in patients diagnosed with glioblastoma post-2016: a SEER population based registry analysis

The EF14 clinical trial reported an improvement in median overall survival (OS) from 16.0 months to 20.9 months in patients with glioblastoma (GBM) who received treatment with tumor treating fields (TTFs). This study evaluates overall survival in a large population-based cohort of patients with GBM before and after FDA approval of TTFs in 2015.

A total of 27,534 patients from the Surveillance, Epidemiology and End Results (SEER) database with GBM who underwent surgery and post-operative radiotherapy were grouped into three diagnosis periods: those diagnosed pre-temozolomide (2000-2004), those diagnosed post-temozolomide (2005-2015), and those diagnosed post-TTFs (2016-2020). Overall survival (OS) was calculated using the Kaplan-Meier method, and multivariate Cox regression models were employed to estimate hazard ratios (HR).

GBM diagnosis in the post-TTFs period was associated with a median OS of 15 months (95% CI 14-15 months) compared to a median OS of 14 months (95% CI 14-14 months, p < 0.001) for GBM diagnosis in the post-temozolomide/pre-TTFs period. 24-months OS was 25.6% (95% CI 24.5-26.8%) in the post-TTFs period and 24.7% (95% CI 24.0-25.4%) in the post-temozolomide/pre-TTFs period. In a multivariate model accounting for clinical characteristics, diagnosis in the post-TTFs period as compared to the post-temozolomide/pre-TTFs period was significantly associated with OS (HR: 0.941, 95% CI 0.912-0.972, p < 0.001).

This population-based cohort demonstrated minimal change in survival for patients diagnosed with GBM before and after FDA approval of TTFs in 2015.