Molecular carcinogenesis of glial brain tumors

Abstract

Glial tumors represent the most common primary central nervous system tumors. They are classified as astrocytomas, oligodendrogliomas, and oligoastrocytomas. They may occur as benign tumors (WHO grade II) or anaplastic tumors (WHO grade III). The most malignant astrocytoma is called glioblastoma and represents WHO grade IV. With the recent publication of the revised fourth edition of the WHO classification of CNS tumors, the molecular characterization of the tumors becomes mandatory. Elementary investigations include the determination of the mutation status of IDH1/2 and co-deletion of 1p/19q. Additional parameters include mutations in the ATRX gene and the TERT promoter. A variety of genetic alterations have been described. Specific focus was laid on epigenetic changes, i.e., altered methylation patterns. Studies related to gene or microRNA (miR) expression in brain tumors are still scarce. Brain tumors pose a challenging task for the clinician and require further broad-minded molecular investigations at various levels.