Trends in glioblastoma treatment, survival, and disparities in access to care in the United States from 2004 to 2019: a National Cancer Database analysis.

Abstract

Objective: Population-based studies of histologically confirmed glioblastoma without molecular classification have demonstrated the doubling of 3-year overall survival (OS) since 2005 despite minimal additions to the treatment armamentarium. The authors aimed to evaluate whether changes in tumor characteristics and treatment patterns were associated with survival outcomes. Additionally, the authors sought to elucidate disparities in access to established and novel therapeutic modalities for patients with glioblastoma.

Methods: The authors queried all patients diagnosed with glioblastoma by histology irrespective of biomarkers from the National Cancer Database and divided patients into 4 equal periods: 2004-2007, 2008-2011, 2012-2015, and 2016-2019. The chi-square test and independent t-test/ANOVA were used to assess associations between categorical and continuous variables, respectively. Differences in OS were tested using the Kaplan-Meier log-rank test. Logistic regression models were constructed to identify predictors of receiving trimodal therapy (surgery, radiation, and chemotherapy) and immunotherapy.

Results: A total of 127,737 patients with glioblastoma were included, of whom 74,387 (58.2%) were males. The proportion of patients receiving trimodal therapy (48.7% vs 60.0%) significantly increased from period 1 to period 4 (p < 0.001). There were higher rates of gross-total resection (28.6% [period 3] vs 33.8% [period 4]), greater total radiation doses of 60 Gy delivered (39.4% [period 1] vs 60.0% [period 4]), increased use of intensity-modulated radiotherapy (16.3% [period 1] vs 62.0% [period 4]), and decreased use of stereotactic radiosurgery (1.5% [period 1] vs 0.8% [period 4]) across the study period (all p < 0.001). Lower total radiotherapy doses (≤ 40.05 Gy) were more commonly administered to elderly patients (≥ 70 years) over time, increasing from 23.4% in period 1 to 42.5% in period 4 (p < 0.001). The use of immunotherapy increased 15-fold (0.4% in period 1 vs 6.2% in period 4, p < 0.001). Comparatively, 2-year OS (17.6% vs 24.6%) and 3-year OS (10.0% vs 15.5%) both increased from period 1 to period 4 (p < 0.001). Patient age, race/ethnicity, education level, insurance status, and treatment facility location/type were independent predictors of receiving trimodal therapy and immunotherapy.

Conclusions: Improvements observed in OS for glioblastoma over the past 2 decades were associated with an increased use of trimodal therapy in accordance with clinical guidelines. Addressing ongoing disparities in the access to established and novel therapeutic modalities for glioblastoma is necessary to optimize outcomes and enhance research discoveries.