RBIO-18. Survival outcomes of hypofractionated and standard radiotherapy in glioblastoma: a National Cancer Database analysis

Abstract BACKGROUND Delivering larger doses per fraction over a shorter period, hypofractionated radiotherapy (HFRT) is included in European Association of Neuro-Oncology guidelines for elderly patients with glioblastoma. This study evaluates HFRT in elderly and non-elderly individuals with glioblastoma using a large US national database cohort. METHODS The 2022 National Cancer Database was queried for patients with histologically confirmed glioblastoma who received standard radiation (60 Gy in 30 fractions) or HFRT (40 Gy in 15 fractions). Kaplan-Meier and multivariate Cox proportional hazards analyses were conducted with stratification by age group (elderly vs. non-elderly), MGMT promoter methylation status, and chemotherapy treatment. Covariates included age, sex, race, ethnicity, Charlson-Deyo score, extent of resection, and tumor size. RESULTS The elderly (≥ 70 years) group included 2,401 individuals, with 1,432 receiving HFRT and 969 receiving standard radiation. Kaplan-Meier analysis demonstrated improved median survival for elderly patients receiving standard radiation compared to HFRT when chemotherapy was pursued (15.01 vs. 10.71 months, p < 0.001), regardless of MGMT promoter methylation status. However, multivariate analyses revealed no survival difference between radiation approaches among elderly patients across all chemotherapy and MGMT promoter methylation subgroupings (p > 0.05). The non-elderly (< 70 years) group consisted of 4,944 patients, with 557 receiving HFRT and 4,387 receiving standard radiation. In univariate analysis, standard radiation was associated with longer median survival than HFRT (18.66 vs. 10.58 months, p < 0.001) regardless of chemotherapy and MGMT promoter methylation status. HFRT was associated with shorter survival across all subgroupings on multivariate analysis. CONCLUSIONS Standard radiation is associated with improved survival compared to HFRT in non-elderly patients with glioblastoma, possibly reflecting poorer baseline health in individuals selected for HFRT. However, no adjusted survival difference was observed between radiation approaches in elderly patients, supporting HFRT as a viable treatment option in this population and warranting further prospective investigation.