Kaplan-Meier's survival analysis showed that TERT promoter mutation (P=0.037), Isocitrate dehydrogenase (IDH) mutation (P<0.001), and 1p/19q codeletion (P<0.001) were associated with favorable overall survival (OS). In the subset of 116 IDH-mutated lower-grade gliomas lacking 1p/19q codeletion, 19 TERT promoter-mutated tumors exhibited longer progression-free survival (PFS) (P=0.027) and OS (P=0.004). Consistent with this observation, in the subset of 97 IDH-mutated astrocytomas, 14 TERT promoter-mutated tumors showed longer PFS (P=0.001) and OS (P=0.001). In contrast, among the subset of 74 IDH wild-type lower-grade gliomas with intact 1p/19q, TERT promoter mutation was associated with shorter PFS (P=0.001) and OS (P=0.001). Similarly, in the subset of 65 IDH wild-type astrocytomas, 16 TERT promoter-mutated tumors exhibited unfavorable PFS (P=0.007) and OS (P=0.008). Our results indicate that when combined with IDH status, TERT promoter mutation contributes to prognostic subgroups of lower-grade astrocytic tumors or 1p/19q intact lower-grade gliomas and this may further refine future molecular classification of lower-grade gliomas.