The Clinical and Molecular Characteristics of Thalamic Gliomas: Retrospective Report of 26 Cases.

OBJECTIVE: Thalamic glioma is a type of midline glioma with poor outcomes. In the present study, we investigated the clinical and molecular features of thalamic gliomas in Chinese patients. METHODS: The data from 26 patients with thalamic glioma who had undergone surgery at Shanghai Huashan Hospital from January 2011 to August 2015 were retrospectively analyzed. Various clinical and molecular factors were evaluated to explore their effects on prognosis. H3K27M mutation status and its association with relevant molecular factors were also investigated. RESULTS: The mean age of the patients was 38.88 years, and no significant difference was found in sex. The most common initial symptoms were headaches (38.46%; 10 of 26) and motor deficits (30.77%; 8 of 26). The H3K27M mutation was identified in 12 patients, and mutant thalamic glioma showed less frequent O-6-methylguanine DNA methyltransferase (MGMT) promoter methylation compared with the wild-type group (P = 0.015; chi(1) test). Multivariate analysis showed that the H3K27M mutation was an independent unfavorable prognostic factor for overall survival. MGMT promoter unmethylation and the TP53 mutation were identified as negative prognostic factors for progression-free survival. CONCLUSIONS: Our results revealed the clinical and molecular characteristics of thalamic glioma in China. Our data have shown the absence of MGMT promoter methylation in H3K27M mutant thalamic glioma, validating it as a hallmark of H3K27M mutant gliomas. In addition, H3K27M mutation was identified as the sole unfavorable prognostic factor on overall survival. MGMT promoter unmethylation and TP53 mutation were identified as independent prognostic factors for progression-free survival.