Diffuse Midline H3 K27-Altered Gliomas in the Spinal Cord: A Systematic Review

Abstract

Background: Gliomas account for 80-90% of all intramedullary spinal cord tumors (IMSCTs). Though rare compared to brain tumors, spinal cord gliomas can cause significant morbidity and mortality. Diffuse midline gliomas (DMGs) with H3 K27M-mutation, first introduced in the 2016 WHO classification, are high-grade tumors with aggressive behavior and poor prognosis. The 2021 updated WHO classification renamed them "diffuse midline glioma, H3 K27-altered" to include other molecular changes. Limited single-institution data on spinal cord DMGs (DMGSCs) hinder comprehensive understanding and optimal treatment protocols. In this review, we summarize clinical and molecular features, management strategies, and survival impact in patients with DMG-SCs.
 Project Methods: A systematic review was performed following the (PRISMA) guidelines. PubMed, Ovid EMBASE, Scopus, and Web of Science were searched. Clinical characteristics, treatment protocols, and outcomes were analyzed.
 Results: A total of 26 studies with 259 patients were included. Most patients were male (63%), diagnosed at a mean age of 32 years (range, 4-72), and tumors were predominately located in the cervical (32%) or thoracic (43%) regions of the spinal cord. Primary management included surgical resection (97%), radiotherapy (78%), and chemotherapy (62%). Most common combination of treatment included surgical resection, radiotherapy, and chemotherapy (47%). The mean overall and progression free survival were 25 (range, 0.1-48) and 14 (range, 0.1-25) months, respectively. Gene alterations included p53 mutation (61%), loss of ATRX (46%), Olig- 2 positive (100%), and GFAP positive (80%). The mean Ki-67/MIB-1 was 23% (12-40%).
 Conclusion/Impact: DMG-SCs affect mostly the adult population and appear to resemble adult DMGs in terms of molecular features, management, and prognosis.