Session Item

Diffuse midline glioma (DMG) is a newly recognized WHO grade IV primary CNS tumor by WHO 2016 classification. The characteristics of DMG include H3K27M mutation glioma, diffuse pattern and midline location. DMG is associated with poor prognosis regardless of histologic grade. Due to its central location, gross total resection is generally not possible. Post-operative treatment with radiotherapy and chemotherapy is suggested but no definite consensus of radiation dose and chemotherapy regimen are established. Nowadays, due to rarity of this disease, there is still limited clinical information and treatment outcome. This study aims to evaluate clinical outcomes and pattern of disease progression in DMG treated with post-operative radiotherapy with chemotherapy.

Newly diagnosed DMG patients treated with post-operative radiotherapy were retrospectively reviewed. Clinical and radiological assessment was performed every 2-3 months using RANO criteria. Pattern of disease progression was classified in field, marginal and distant progression base on radiation treatment planning. Overall survival (OS) and progression free survival (PFS) was evaluated using Kaplan-Meier method.  

 Between September 2016 and September 2019, 9 patients with biopsy-proven DMG with H3K27M mutation were retrospectively reviewed. DMGs were located in thalamus, pons and spinal cord, 55%, 33% and 11%, respectively. Mean age of the patient was 31 years (12-61 years). All patients had completed radiotherapy using intensity modulated radiotherapy (IMRT) or volumetric modulated arc therapy (VMAT) technique. The median radiation dose was 60 Gy in 30 fractions for brain lesion and 50 Gy in 25 fractions for spinal cord lesion. Fifty-five percent of the patients received chemotherapy included temozolomide and BCNU. Median follow up duration was 14.2 months (2.8-30.5 months). Median progression free survival was 21.1 months while median overall survival was not reached. 1-year and 2-year progression free survival were 87.5% and 43.8%, respectively. In-field progression of disease was detected in 2 patients (22%). No marginal and distant progression were detected. 1 of 2 of progressed patients underwent re-irradiation.

The initial clinical outcome of patients with DMG who underwent post-operative radiotherapy and chemotherapy yielded good progression free survival and overall survival compared with glioblastoma WHO grade IV in previously reported literature. The common progression pattern is in-field disease progression.