Prognostic Impact of Calcification, Corpus Callosum Invasion, and CDKN2A/B Hemizygous Deletion in Oligodendroglioma: A Single-center Retrospective Study

Oligodendrogliomas generally have a better prognosis than other adult-type diffuse gliomas. However, although several clinical and radiological prognostic factors have been reported, long-term outcomes remain heterogeneous, and decisions regarding postoperative treatment remain challenging because of concerns about long-term adverse effects. This study aimed to explore prognostic factors by analyzing clinical, radiological, therapeutic, and genetic data from a single-institution cohort.We retrospectively reviewed adult patients (≥18 years) with isocitrate dehydrogenase-mutant and 1p/19q-codeleted oligodendrogliomas who underwent surgical resection at our institution between 1999 and 2021, with available preoperative magnetic resonance imaging and computed tomography. CDKN2A/B copy number status was assessed using multiplex ligation-dependent probe amplification and confirmed by fluorescence in situ hybridization. Overall survival and progression-free survival were analyzed using the Kaplan-Meier method and Cox proportional hazards models. For overall survival, simple multivariable Cox models adjusted for age and Karnofsky Performance Status were constructed.A total of 32 patients were included. The median age was 40 years, and the median Karnofsky Performance Status was 90. Calcification and corpus callosum invasion were observed in 46.9% and 40.6% of cases, respectively, and CDKN2A/B hemizygous deletion was identified in four cases. The 5-year progression-free survival was 62.0%, and the 5-year overall survival was 86.5%. On univariable Cox analysis for overall survival, corpus callosum invasion, calcification, and CDKN2A/B hemizygous deletion were significant adverse prognostic factors. In simple multivariable Cox models, CDKN2A/B hemizygous deletion remained associated with shorter overall survival.Calcification, corpus callosum invasion, and CDKN2A/B hemizygous deletion may be prognostic markers in oligodendroglioma.