Clinical guidelines generally recommend radiotherapy with concurrent or sequential chemotherapy, including for grade 2 and grade 3 IDH-mutant, 1p/19q co-deleted oligodendroglioma and IDH-mutant astrocytoma (Table 2), given the benefits of chemoradiotherapy over mono-radiotherapy (79, 94, 95). Here, IDH1 is linked to oligodendroglioma.