Reclassification of Mixed Oligoastrocytic Tumors Using a Genetically Integrated Diagnostic Approach

Anaplastic astrocytoma (AA), anaplastic oligoastrocytoma (AOA), and anaplastic oligodendroglioma (AO) are the major histological subtypes of World Health Organization grade III gliomas. More evidence suggests that AOA is unlikely to be a distinct entity, and re-evaluation of this issue has been recommended. In this study, we divided AOA into 2 subgroups, according to molecular biomarkers, and compared the survivals between them. One hundred nine patients with histological diagnosis of anaplastic gliomas enrolled in the study. Molecular biomarkers evaluated included 1p/19q codeletion and IDH1/2 mutation. Kaplan-Meier plots were compared by log-rank method. There was no significant difference between AA and AOA with regard to the frequencies of biomarkers and survival plots. According to the status of biomarkers, AOA was classified into 2 subgroups (AOA1 and AOA2), for which Kaplan-Meier plots were significantly different (P = .001 for both progression-free survival [PFS] and overall survival [OS]). AOA1 with 1p/19q codeletion and/or IDH1/2 mutation showed similar Kaplan-Meier plots with AO (P = .169 for PFS and P = .523 for OS). AOA2 without either biomarker showed similar Kaplan-Meier plots with AA (P = .369 for PFS and P = .271 for OS). In addition, patients with AO and AOA1 had significantly longer PFS and OS than did patients with AA and AOA2 (P < .001 for both PFS and OS). AOA is a heterogeneous group and can be divided into 2 subgroups with significantly different prognoses according to the status of 1p/19q and IDH1/2. This will be helpful in estimating patients' prognosis and guiding reasonable therapy for patients with anaplastic gliomas.