Brain and other central nervous system tumours
The brain and the spinal cord make up the central nervous system (CNS). Different types of tumours can start in the CNS. They are named after the type of cell or part of the brain/spinal cord from which they arise. Even though these cancers start in the CNS, they are all different cancers, and need to be treated differently.
This section focuses on brain and CNS tumours that start in the CNS. It doesn’t include information about cancers that spread, or metastasise, to the brain or CNS.
Gliomas develop from glial cells. These are cells in the CNS and the peripheral nervous system that don’t produce electrical impulses. There are different types of glial cells.
Astrocytomas develop from a glial cell called an astrocyte. An astrocyte is a cell that supports the nerve cells in the brain.
The terms ‘astrocytoma’ and ‘glioma’ are often used interchangeably.
The most common types of astrocytomas are:
- juvenile pilocytic astrocytoma (JPA), a slow-growing tumour, usually in the back of the brain (cerebellum). This type of tumour is referred to as a low grade glioma.
- glioblastoma multiforme (GBM), a fast-growing tumour that usually starts in the upper part of the brain. This type of tumour is referred to as a high grade glioma.
- anaplastic astrocytoma, a fast-growing tumour that usually starts in the upper part of the brain. This type of tumour is referred to as a high grade glioma.
Diffuse midline glioma (DMG) includes tumours previously referred to as Diffuse intrinsic Pontine Glioma (DIPG)
Diffuse midline glioma (DMG) is characterised by K27M mutations. They are most commonly located in the brainstem and when located there used to be called diffuse intrinsic pontine gliomas (DIPGs). The brain stem, which ‘connects’ the brain and the spinal cord, is the control centre for vital body functions such as the heart beating and breathing.
Optic pathway glioma
Optic pathway gliomas can start in either the:
- optic nerve, which connects the brain with the eyes
- nerve pathways in the brain that control vision.
Ependymomas start from ependymal cells. These cells line the fluid-filled areas of the brain (called the ventricles) and spinal cord. The fluid in these areas is called cerebrospinal fluid. There are many subtypes of ependymomas, depending on where they start in the brain. If they start in the upper part of the brain, they are called supratentorial ependymomas. The majority of supratentorial ependymomas are called RELA fusion–positive ependymomas. If they start in the back part of the brain, they are called posterior fossa ependymomas. This is most commonly seen in children and our understanding of posterior fossa ependymomas is evolving and will soon be split into molecularly distinct subgroups. Spinal cord ependymomas are most commonly seen in adults.
Ependymomas can spread to other parts of the CNS.
Medulloblastomas develop from a type of nerve cell in the back of the brain (cerebellum). They tend to be fast-growing tumours and often spread to other parts of the brain or spinal cord. At the molecular (genetic) level, it is now recognised that there are four main distinct subgroups of medulloblastoma called WNT medulloblastoma, Sonic Hedgehog (SHH) medulloblastoma, Group 3 medulloblastoma and Group 4 medulloblastoma.
Rare brain and CNS tumours
There are several types of rare brain and spinal cord tumours, including:
- atypical teratoid rhabdoid tumours (ATRT)
- CNS Embryonal tumours (this includes tumours previously referred to as primitive neuroectodermal tumours (CNS-PNET). Our understanding of this complex group of tumours is evolving and will soon be split into several molecularly distinct tumour types
- embryonal tumor with multilayered rosettes (ETMR), CNS germ cell tumours.