P07.16 Prognostic value of contrast enhancement and histopathological grading in diffuse gliomas depends on IDH1/2 mutation

Abstract

AbstractBackground:Contrast enhancement (CE) and anaplasia have been reported to indicate poor outcome in diffuse glioma. Recently, mutational status of the IDH1/2 gene and loss of heterozygosity on chromosome 1p/19q (LOH1p/19q) have gained relevance for the evaluation of clinical outcome. Currently, a three-way classification based on IDH1/2 mutation and LOH 1p/19q has gained further importance and will eventually supersede the current WHO grading system in terms of risk stratification and treatment planning. Thus, we aimed in the present study to re-evaluate CE and histopathological WHO grading as risk factors for survival within the framework of these molecular markers.Methods:332 patients with diffuse glioma WHO grade II (n=189) or grade III (n=143) were stratified into 3 groups: IDH1/2 wild type (n=118), IDH1/2 mutated with (n=123) and without (n=91) LOH1p/19q. Preoperative magnetic resonance (MR) imaging was reviewed for presence of CE. Univariate and multivariate analyses were conducted taking into account CE, WHO grading, molecular as well as age, Karnofsky performance status, surgical procedure and adjuvant therapy.Results:In multivariate analysis, CE was not associated with OS in IDH1/2 wild type tumors whereas histopathological WHO grading had a strong independent prognostic value on OS in (p=0.001). In gliomas with IDH1/2 mutation, CE independently predicts shorter survival (p=0.04) and this effect seems to be especially pronounced in the IDH1/2 mutated group without LOH 1p/19q.Conclusions:In patients with diffuse gliomas WHO grade II/III and IDH1/2 wildtype, CE is not associated with survival in contrast to WHO grading. In patients with an IDH1/2 mutation, presence of CE on initial MRI is linked to inferior survival while grading is not.