Abstract
BACKGROUND Traditionally, gliomas were classified based on histopathological features alone. The revised World Health Organization (WHO) classification of tumors of the central nervous system from 2016 integrated molecular features into the histopathological diagnosis. OBJECTIVE To summarize key aspects of the WHO classification from 2016 and implications for the clinical management of glioma patients. An overview of novel treatment approaches is also provided. RESULTS Oligodendrogliomas are defined independently of their histopathological appearance by the simultaneous presence of a mutation in the isocitrate dehydrogenase (IDH)-1 or IDH-2 gene and co-deletion of chromosome arms 1p and 19q. Astrocytomas are classified based on the presence or absence of mutations in IDH. Astrocytic tumors with wild-type IDH comprise approximately 90% of glioblastomas, the most common malignant primary brain tumor in adults. The extent of resection is a favorable prognostic factor in diffuse gliomas. Postoperatively, most patients are treated with a combination of radiotherapy and alkylating agent chemotherapy. In IDH wild-type astrocytic tumors, hypermethylation of the promoter of the DNA repair protein O-methylguanine-DNA methyltransferase (MGMT) gene is predictive for benefit from the alkylating agent temozolomide. Most novel treatment approaches that are currently being assessed in clinical trials aim at reprogramming the immune system to specifically eradicate tumor cells, but the efficacy of such approaches in gliomas remains to be demonstrated. DISCUSSION To date the classical treatment modalities comprising surgery, radiotherapy and chemotherapy remain the mainstay of glioma treatment. The integration of molecular features into the classification of gliomas is a basis for personalized treatment approaches.
Wirsching, H-G