A population-based study of high-grade gliomas and mutated isocitrate dehydrogenase 1.

High-grade gliomas have a dismal prognosis, and prognostic factors are needed to optimize treatment algorithms. In this study we identified clinical prognostic factors as well as the prognostic value of isocitrate dehydrogenase 1 (IDH1) status in a population-based group of patients with high-grade gliomas. Using the Danish Cancer Registry and the Danish Pathology Databank we identified 359 patients: 234 had WHO grade IV gliomas, 58 had WHO grade III gliomas, and 67 were diagnosed clinically. Mutated IDH1 was predominantly observed in oligodendroglial tumors (WHO grade III). Patients with mutated IDH1 had a significantly better outcome than patients with wildtype IDH1: 2-year OS 59% and 18%, respectively (HR 0.38, 95% CI 0.21-0.68). However, when adjusting for other prognostic factors, IDH1 status was not a significant independent prognostic factor (HR=0.58, 95% CI 0.32-1.07). Young age, absence of neurological deficit, performance status 0-1, tumor not crossing the midline, and receiving post-surgical treatment were significant independent indicators of a good prognosis in multivariate analysis. This population-based study could not demonstrate IDH1 status to be an independent prognostic factor in high-grade gliomas when adjusting for the effect of classic prognostic factors.