Long-Term Outcome of Molecularly Defined Oligodendrogliomas

BACKGROUND AND OBJECTIVES: Molecularly defined oligodendrogliomas are rare tumors whose prognosis has improved over time because of more effective treatments. However, several aspects of management are still controversial, and studies with long-term follow-up are needed. The main aim of this study was to analyze and compare the natural history and management of patients with OG2 and OG3 and define which factors have the strongest effect on outcome. METHODS: We reviewed an institutional retrospective cohort (1996-2024) of patients with molecularly defined OG2 and OG3 according to World Health Organization 2021. We retrieved information on baseline clinical features, MRI characteristics (i.e., presence and pattern of contrast enhancement), extent of resection, initial treatment modalities after surgery, and management at progression. The relationships of these factors with progression-free survival (PFS) and overall survival (OS) were studied with univariate and multivariate analyses. RESULTS: = 0.016), whereas tumor grade did not. Temozolomide alone as initial treatment of high-risk OG2 and OG3 with large residual tumor after surgery was not detrimental for survival. The same was true for observation in a small group of young patients with nonenhancing OG3 who have undergone complete resection and with only focal areas of malignancy (OG3f). DISCUSSION: -mutant 1p/19q-codeleted oligodendrogliomas receiving standard treatments could serve as a benchmark for comparison with new IDH inhibitors in future clinical studies.