Late effects of radiotherapy for IDH mutant diffuse glioma

This dissertation examines treatment outcomes after radiotherapy for IDH mutated diffuse glioma, a rare brain tumor with a peak incidence between age 30 to 50. Despite a relatively long survival, these tumors remain incurable at present. The research focuses on neurocognitive and radiological outcomes after radiotherapy.
Chapter 1 introduces IDH-mutant gliomas, their classification, and advancements in treatment. Chapter 2 investigates a complication model for memory dysfunction after radiotherapy in grade 2 diffuse glioma patients based on hippocampal dose. This model was found to overpredict the risk of neurocognitive decline. Chapter 3 assesses cognitive function in 49 patients with IDH-mutant grade 2 and 3 gliomas. While no significant decline over time was found, a higher mean brain dose was related to lower test scores. Chapter 4 explores pseudoprogression, a phenomenon where MRI lesions post-radiotherapy may mimic disease progression. This was found to be frequent, particularly in oligodendroglioma, and its incidence increases with observed time. Chapter 5 examines disease progression in relation to radiotherapy margins. While recurrences were mostly situated within the original treatment volume, the findings do not support reducing treatment margins below 10 mm. Chapter 6 summarizes the findings, emphasizing the need for validated models and continued data stewardship.