Glioblastoma (GBM) is the most devastating type of human cancers with a median survival time ranging from 12-18 months following maximal therapies . Glioma is classified into four malignancy grades according to histological features; the low-grade tumors including WHO Grade I (localized gliomas) and WHO Grade II (diffuse astrocytoma or oligodendrogliomas), and the high-grade tumors including WHO Grades III (anaplastic gliomas) and WHO Grade IV (GBM). The concept of malignant progression is usually applied to secondary GBM which is originally a grade II or grade III glioma and is diagnosed as GBM at the time of recurrence. Most of this tumor carries IDH1 mutation, in contrast to primary GBM without carrying isocitrate dehydrogenase-1 (IDH1) mutation which is the majority of GBM.Although GBM is considered to be a final stage of tumorigenesis collecting many types of genetic alterations in the oncogenes and tumor suppressor genes, large variations of survival time exist within the same category of GBM. Recently, the Cancer Genome Atlas (TCGA) showed that GBM can be categorized into four subclasses based on molecular genetic properties, which is partially relevant to patient survival.