A long-term follow-up of the phase 3 EORTC 22033-26033 trial found that radiotherapy and dose-dense temozolomide provide similar survival outcomes for patients with high-risk, low-grade glioma. After a median follow-up of 13.1 years, overall survival was 6.6 years with radiotherapy and 8.0 years with temozolomide, while progression-free survival was 3.6 years and 3.1 years, respectively. Neither difference was statistically significant.
Researchers analyzed tumor samples using the updated 2021 WHO classification and found that molecular subtype was the strongest predictor of patient outcomes. Patients with IDH-mutant, 1p/19q-codeleted oligodendroglioma had the best survival, with median overall survival reaching nearly 13 to 15 years. Those with IDH-mutant, noncodeleted astrocytoma had a median overall survival of about 6.6 years regardless of treatment. Patients with the more aggressive IDH-wild-type tumors appeared to benefit more from temozolomide than radiotherapy.
The findings highlight that tumor biology is more important than the initial treatment choice in predicting outcomes. Researchers say molecular classification should guide treatment decisions, while newer approaches, including combined radiotherapy and chemotherapy and emerging IDH-targeted drugs such as vorasidenib, are expected to further improve care.