Subsequent post hoc molecular analysis of the RTOG 9802 trial, conducted on 42% of enrolled cases, further highlighted a significant survival advantage in patients with molecularly confirmed IDH-mutant, 1p/19q-codeleted oligodendrogliomas (hazard ratio [HR], 0.21; p = 0.029) (21). The gene discussed is IDH1; the disease is oligodendroglioma.