Find Out More About Brain Tumor Types
Brain tumor types include all tumors inside the cranium or in the central spinal canal. They are created by an abnormal and uncontrolled cell division, normally either in the brain itself (neurons, glial cells (astrocytes, oligodendrocytes, ependymal cells, myelin-producing Schwann cells), lymphatic tissue, blood vessels), in the cranial nerves, in the brain envelopes (meninges), skull, pituitary and pineal gland, or spread from cancers primarily located in other organs (metastatic tumors). There are more than 120 of brain tumor types. Today, most medical institutions use the World Health Organization (WHO) classification system to identify brain tumors. The WHO classifies brain tumors by cell origin and how the cells behave, from the least aggressive (benign) to the most aggressive (malignant). Some tumor types are assigned a grade, ranging from Grade I (least malignant) to Grade IV (most malignant), which signifies the rate of growth. There are variations in grading systems, depending on the tumor type. The classification and grade of an individual tumor help predict its likely behavior.
Brain tumors are classified depending on the exact site of the tumor, the type of tissue involved, whether they are noncancerous (benign) or cancerous (malignant), and other factors. Sometimes, tumors that start out being less invasive can become more invasive.Tumors may occur at any age, but many brain tumor types are most common in a certain age group. In adults, gliomas and meningiomas are most common. Gliomas come from glial cells such as astrocytes, oligodendrocytes, and ependymal cells. The gliomas are divided into three types:
* Astrocytic tumors include astrocytomas (less malignant), anaplastic astrocytomas, and glioblastomas (most malignant).
* Oligodendroglial tumors also can vary from less malignant to very malignant. Some primary brain tumors are made up of both astrocytic and oligodendrocytic tumors. These are called mixed gliomas.
* Glioblastomas are the most aggressive type of primary brain tumor.
Other primary brain tumors in adults are rare. These include: Ependymomas, Craniopharyngiomas, Pituitary tumors, Primary lymphoma of the brain, Pineal gland tumors and Primary germ cell tumors of the brain.
Only 5 – 10% of primary brain tumors are associated with genetic disorders. These inherited conditions and associated genes include:
* Von Recklinghausen disease, also called neurofibromatosis 1 (NF1 gene) and neurofibromatosis 2 (NF2 gene)
* Turcot syndrome (APC gene)
* Gorlin syndrome, also called basal cell naevus syndrome (PTCH gene)
* Tuberous sclerosis (TSC1 and TSC2 genes)
* Li-Fraumeni syndrome (TP53 gene)
Neurofibromatosis 1 is associated with about 15% of cases of pilocytic astrocytomas, the most common type of childhood glioma. Both of these result from defects in specific tumor suppressor genes. These genetic conditions specifically linked with certain brain tumor types.