EPID-21. INCORPORATING RECEIPT OF STANDARD-OF-CARE AS A KEY VARIABLE IN POPULATION-BASED STUDY OF GLIOBLASTOMA SURVIVAL

Abstract Object Populational database research with real-world settings offers epidemiologic insight at scales that cannot be easily recapitulated, especially for rare cancers such as glioblastoma. However, most survival studies were conducted without consideration whether the patients received standard of care (SOC). METHODS Survival analysis was performed using National Cancer Database (NCDB) and stratified Methyl-guanine-methyl transferase (MGMT) promotor methylation. Glioblastoma age < 40 excluded to minimize prognostic impact isocitrate dehydrogenase (IDH) mutations. SOC defined receipt chemotherapy radiation within 2-6 weeks surgical biopsy or resection. Sensitivity analyses allowing start date differ by 0, 3, 5, 10 days. RESULTS Within NCDB (N = 11231), 54.7% newly diagnosed glioblastoma did not receive SOC. The median time (MST) estimates significantly shorter all (10.9, IQR: 4.3-21.5, months) relative treated (15.3, 8.6-26.2, months; p 0.001). MST remain stable in sensitivity 10-day discrepancy between date. These results recapitulated SEER-Medicare database. MGMT methylated unmethylated after 21.0 14.5-mo, respectively. overall MGMT-specific mirror those reported arms five recent randomized controlled studies. Analysis indicates benefit immunotherapy (HR: 0.90, 0.020) while absent 0.97, 0.644) - latter observation more reflective trial clinical experiences. CONCLUSION populational study can misleading information on