Disparities in receipt of modern concurrent chemoradiotherapy in glioblastoma.

Temozolomide given concurrently with radiation after resection/biopsy improves survival in glioblastoma (GBM). The disparities in receipt of adjuvant single-agent chemotherapy and their association with outcome have not been well established. Observational study of a prospectively collected database, the National Cancer Database (NCDB), from 1998 to 2012 with median follow-up 12.4 months. Among the 114,979 patients in the NCDB with GBM, 44,531 patients were analyzed for disparities, and 28,279 patients were analyzed for overall survival (OS). Associations were assessed in a multivariable Cox proportional hazards regression model. Survival was estimated using the Kaplan-Meier method. Median age was 58 years. Chemotherapy use was associated with male gender, white race, younger age (≤50), higher performance status (≥70), more extensive surgery, insurance status, higher income/education, and treatment at academic centers (all p < 0.05). We found improved OS associated with type of insurance (private insurance HR 0.91, 95 % CI 0.85-0.96 and Medicare HR 1.24, 95 % CI 1.16-1.33, both p < 0.01 compared to uninsured) and treatment at academic programs (HR 0.86; p < 0.01). MGMT methylation status predicted improved OS (HR 0.54; 95 % CI 0.41-0.70, p < 0.01). 1-year OS for patients receiving chemotherapy was 55.9 % versus 35.3 % for those without (p < 0.0001). After adjustment for confounders, chemotherapy use remained associated with improved OS (HR 0.64, 95 % CI 0.63-0.66, p < 0.01). Chemotherapy utilization increased from 26.9 to 93.3 % during the study period. We have identified specific disparities in the use of chemotherapy that may be targeted to improve patient access to care. Widespread adoption of adjuvant chemoradiotherapy after resection or biopsy for GBM appears to improve OS.