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

Purpose Oligodendrogliomas generally have a better prognosis than other adult-type diffuse gliomas. However, few prognostic factors have been established, and decisions regarding postoperative treatment remain challenging due to concerns about long-term adverse effects. This study aimed to identify prognostic factors by analyzing clinical, radiological, therapeutic, and genetic data from a single-institution cohort. Methods We retrospectively reviewed adult patients (≥ 18 years) with isocitrate dehydrogenase (IDH)-mutant and 1p/19q-codeleted oligodendrogliomas who underwent surgical resection at our institution between 1999 and 2021, with available preoperative MRI and CT. CDKN2A/B copy number status was assessed using multiplex ligation-dependent probe amplification (MLPA) and confirmed by fluorescence in situ hybridization (FISH). The impact on overall survival (OS) and progression-free survival (PFS) was evaluated using Kaplan–Meier survival analysis and the Cox proportional hazards model. Results Thirty-two patients were included. The median age was 40 years, and the median Karnofsky Performance Status (KPS) was 90. Calcification and corpus callosum invasion were observed in 46.9% and 59.4% of cases, respectively. CDKN2A/B hemizygous deletion was identified in four cases. The 5-year PFS was 62.0%, and the 5-year OS was 86.5%. On univariate Cox proportional hazards analysis, calcification (p = 0.046), corpus callosum invasion (p = 0.022), and CDKN2A/B hemizygous deletion (p = 0.006) were significantly associated with shorter OS. Conclusion Calcification, corpus callosum invasion, and CDKN2A/B hemizygous deletion appear to be important prognostic factors in oligodendroglioma.