Male sex (HR, 1.72; 95% CI, 1.18–2.52; p = 0.01) was major risk factor for postoperative glioma recurrence or death in level 1 (WHO grade 1 or 2); whereas Olig2 positivity (HR, 0.78; 95% CI, 0.64–0.95; p = 0.01) and postoperative chemotherapy or radiotherapy (HR, 0.38; 95% CI, 0.29–0.49; p < 0.001) were protective factors in level 3 (WHO grade 4). This evidence concerns the gene OLIG2 and glioma.