HOUT-05. COMPARING OUTCOMES OF ADULT DIFFUSE MIDLINE GLIOMAS TO GLIOBLASTOMA (GBM) IN YOUNG PATIENTS

Abstract

Abstract Diffuse midline gliomas are a diagnostic entity with astrocytic tumors in a midline location and in the pediatric age group they have been associated with poor outcomes. There is ongoing debate if adults with diffuse midline gliomas also have a poor prognosis particularly as complete surgical resection is often not achievable in these patients. One of the limitations of looking at case-series based outcomes with these patients is that the incidence of these tumors has a skew towards younger patients and recent case-series with observed better than expected outcomes, might be subject to influence from this parameter. To better compare outcomes of these patients we reviewed our institutional tumor registry to identify 31 patients with diffuse midline gliomas from January 2010 to December 2017. We also identified a contemporaneous consecutive series of 46 patients of age ≤ 55 with a diagnosis of GBM, as the control group for comparison. Both groups were comparable in median age (53 vs 50), gender distribution and median Karnofsky Performance Status (80 vs 90). But fewer resections were performed on diffuse midline gliomas (35.5% vs 80%). Our results indicate that patients with a diffuse midline glioma have a higher likelihood of a poorer outcome with a median overall survival of 52 vs 91 weeks in the control. The hazard ratio for death in the diffuse midline glioma cohort as compared to the control was 1.68 (95% CI – 0.97–2.91, log-rank P value = 0.038). The 2-year survival rate was also lower in the diffuse midline glioma with 22.6% vs 39.1% in the control. This poorer outcome could be related to the slightly lower median performance status or the lack of complete resection in diffuse midline glioma patients. Additional analysis is being planned to genetically differentiate these patients and identify possible prognostic indicators.