2.Glioblastoma

Glioblastomas (GBMs) is the most common and primary aggressive brain tumor. Glioblastoma is shown the **Figure 6**. Glioblastoma accounts for 45.6% of primary malignant brain tumors. Typical molecular changes in glioblastoma include mutation in gene-regulating receptor tyrosine kinase (RTK) / phosphoinositide 3-kinase (PI3K), p53, and retinoblastoma protein (RB) signaling [71]. Secondary glioblastoma is a kind of glioblastoma that develops in younger people when a previous malignancy, such as grade II astrocytoma or anaplastic astrocytoma, somatically mutates into a glioblastoma [74].

**Figure 7.** *Oligodendroglioma.*

#### 3.Oligodendroglioma

Oligodendroglioma is a rare form of brain tumor. The brain is made up of many supporting cells that are called glial cells. Any tumor of these glial cells is called glioma. A tumor that arises from the glial cells (oligodendrocyte cells) is called oligodendroglioma [72]. Oligodendrogliomas vary from other glial tumors in their molecular genetic makeup. On chromosome 1p and chromosome 19q, LOH is seen often in oligodendrogliomas of all grades [75]. Oligodendroglioma is shown in **Figure 7.**
