Clinical and survival differences between thalamic glioblastoma and thalamic diffuse midline glioma, H3 K27-altered

The 2021 WHO classification describes a specific subgroup of diffuse midline glioma, H3 K27-altered (DMG-H3 K27-altered), which arises in the thalamus or other midline structures. To date, the prognosis of thalamic DMG-H3 K27-altered remains controversial, and no studies have compared its overall survival (OS) with that of glioblastoma (GBM). The present study aimed to compare the clinical features and survival outcomes of patients with thalamic DMG-H3 K27-altered and those with thalamic GBM.

This was a retrospective, single-center study. The clinical characteristics, pathological findings, treatment modalities, and prognostic outcomes of the patients were summarized. Survival analyses were conducted using the Kaplan-Meier and Cox regression analyses.

We screened 44 patients diagnosed with thalamic GBM, and 43 with thalamic DMG-H3 K27-altered. Compared with GBM, patients with DMG-H3 K27-altered were significantly younger (median age: 40 vs. 49 years, p = 0.039), exhibited lower Ki67 index, and had less MGMT promoter methylation rates. The median OS was significantly prolonged in thalamic DMG-H3 K27-altered compared with GBM among patients treated according to the Stupp protocol (26.3 vs. 14.7 months, p = 0.019). In patients with thalamic DMG-H3 K27-altered group, slight or no enhancement on magnetic resonance imaging (MRI) was significantly associated with prolonged OS (26.3 vs. 13.7 months, p = 0.031).

The OS of thalamic DMG-H3 K27-altered was superior to GBM among patients who received treatment according to the Stupp-protocol. Slight or no enhancement on MRI was significantly associated with prolonged OS in patients with thalamic DMG-H3 K27-altered.