The prognostic significance and genetic characteristics of H3 K27M–mutant diffuse midline gliomas (DMGs) in different anatomical locations requires further clarification. In this study, the authors integrated published data to investigate the differences between brainstem, thalamic, and spinal cord tumors.

PubMed and Web of Science databases were used to search for eligible articles. Studies were included if they provided individual patient data of H3 K27M–mutant DMGs with available tumor locations. Hazard ratios (HRs) and 95% confidence intervals (CIs) were computed to investigate the survival of each subgroup.

Eight hundred four tumors were identified, including 467, 228, and 109 in the brainstem, thalamus, and spine, respectively. Brainstem tumors were primarily observed in young children, while patients with thalamic and spinal cord tumors afflicted older patients. The Ki-67 labeling index was highest in brainstem tumors. Compared to patients with brainstem tumors, those with thalamic (HR 0.573, 95% CI 0.463–0.709; p < 0.001) and spinal cord lesions (HR 0.460, 95% CI 0.341–0.621; p < 0.001) had a significantly better survival. When patients were stratified by age groups, superior overall survival (OS) of thalamic tumors was observed in comparison to brainstem tumors in young children and adolescents, whereas adult tumors had uniform OS regardless of anatomical sites. Genetically, mutations in HIST1H3B/C (H3.1) and ACVR1 genes were mostly detected in brainstem tumors, whereas spinal cord tumors were characterized by a higher incidence of mutations in the TERT promoter.

This study demonstrated that H3 K27M–mutant DMGs have distinct clinical characteristics, prognoses, and molecular profiles in different anatomical locations.

H3 K27M突变型弥漫性中线胶质瘤（DMGs）在不同解剖位置的预后意义和遗传特征需要进一步阐明。在这项研究中，作者整合了已发表的数据来研究脑干、丘脑和脊髓肿瘤之间的差异。

PubMed 和 Web of Science 数据库用于搜索符合条件的文章。如果研究提供了具有可用肿瘤位置的 H3 K27M 突变 DMG 的个体患者数据，则纳入研究。计算风险比 (HRs) 和 95% 置信区间 (CIs) 以研究每个亚组的生存率。

共发现 804 个肿瘤，其中脑干、丘脑和脊柱分别有 467、228 和 109 个肿瘤。脑干肿瘤主要在幼儿中观察到，而丘脑和脊髓肿瘤患者则折磨老年患者。Ki-67 标记指数在脑干肿瘤中最高。与脑干肿瘤患者相比，丘脑（HR 0.573, 95% CI 0.463–0.709; p < 0.001）和脊髓病变患者（HR 0.460, 95% CI 0.341–0.621; p < 0.001）的生存期明显更好。当按年龄组对患者进行分层时，与幼儿和青少年的脑干肿瘤相比，丘脑肿瘤的总生存期 (OS) 更高，而无论解剖部位如何，成人肿瘤的总生存期均一致。HIST1H3B/C (H3.1)基因突变和ACVR1基因主要在脑干肿瘤中检测到，而脊髓肿瘤的特征是TERT启动子的突变发生率较高。

该研究表明，H3 K27M 突变 DMG 在不同解剖位置具有不同的临床特征、预后和分子谱。