Astrocytoma showed less difference of OS among patients when TMZ was used with IDH1 mutant phenotype (26.5 for no TMZ group vs 31.5 months for TMZ group: log-rank p = 0.9), while on the other hand, patients with the same histology had relatively better OS for IDH wild-type phenotypes (6.0 for no TMZ group vs 28.5 months for TMZ group: log-rank p = 0.09). Here, IDH2 is linked to astrocytoma (excluding glioblastoma).