Background: Glioblastoma multiforme (GBM) is a highly aggressive brain tumor with a poor prognosis. Radiation therapy (RT) and temozolomide (TMZ) are standard treatments, but their impact on cognitive function is not well understood.


Objective: To investigate the effects of radiation dose and TMZ dose on cognitive function in patients with GBM treated with RT and TMZ.


Methods: This retrospective study included 162 patients with GBM treated with RT and TMZ between 2018 and 2023. Cognitive function was assessed using a comprehensive battery of neuropsychological tests, and MRI-based measures of cognitive function were obtained. Patients were categorized into three groups based on radiation dose received: low dose (< 50 Gy), moderate dose (50-60 Gy), and high dose (> 60 Gy). Follow ups were made up to 8 to 12 months after chemoradiotherapy.


Results: Patients in the high dose group performed significantly worse on executive function and memory tests, and had reduced white matter integrity and increased white matter hyperintensity volume compared to the low dose group. Higher TMZ doses were associated with poorer cognitive outcomes in executive function, memory, and reduced hippocampal volume. Linear regression analysis showed that higher radiation doses were associated with poorer cognitive outcomes in memory, and higher TMZ doses were associated with poorer cognitive outcomes in executive function, memory, and reduced hippocampal volume.


Conclusion: This study suggests that higher radiation doses and TMZ doses are associated with poorer cognitive outcomes in patients with GBM. These findings have important implications for the management of GBM, highlighting the need to minimize radiation dose and TMZ dose to prevent cognitive decline. Future studies are needed to confirm these findings and to explore strategies to mitigate the cognitive effects of RT and TMZ in patients with GBM.