Early Initiation of Radiation Therapy Improves Survival in Elderly Patients With Glioblastoma

BACKGROUND AND OBJECTIVES: To study the impact of early initiation of radiation therapy (RT) in elderly patients with newly diagnosed glioblastoma. METHODS: A total of 56 elderly patients (aged 65 and older) diagnosed with isocitrate dehydrogenase (IDH)-wildtype glioblastoma were analyzed from a prospective registry from 2020 to 2024. Survival analysis was conducted to evaluate the impact of timing of RT initiation after surgical resection on survival outcomes. A specific cutoff point for RT initiation was evaluated using the log-rank test, with P -values adjustment for multiple comparisons using the false discovery rate approach. Kaplan-Meier curves were used to illustrate survival distributions. Associations of various risk factors with survival were initially examined through univariate Cox regression models, followed by multivariate analysis to assess the combined effects of these factors. The results were reported as hazard ratios with 95% CIs. RESULTS: Elderly patients with glioblastoma who underwent initiation of RT < 20 days from date of surgery demonstrated improved overall survival (OS) ( P = .0460) and progression-free survival (PFS) ( P = .0075) in our cohort. Multivariate analysis demonstrated that adjuvant temozolomide significantly affected both OS ( P = .0038) and PFS ( P = .0133). Conventionally fractionated RT consisting of 60 Gy in 30 fractions demonstrated significantly improved PFS ( P = .0164) in patients who underwent early initiation of RT (<20 days). By contrast, hypofractionated RT delivering 40 Gy in 15 fractions did not show significantly improved PFS ( P = .0509) in patients who underwent early initiation of RT (<20 days). CONCLUSION: Early initiation of RT in elderly patients with newly diagnosed glioblastoma improves both OS and progression-free survival. Timing of RT is particularly of significance in this patient population who may not be optimal candidates for systemic chemotherapy.