The brain and primary brain tumours

The brain has different parts. These control different functions in the body. The spinal cord passes messages between the brain and the body.

Primary brain tumours are tumours that start in the brain. These tumours can be:

  • benign (not cancer) – these are slow-growing, unlikely to spread and may not cause symptoms for a long time. Sometimes they are called low-grade.
  • malignant (cancer) – these are faster growing and may spread into nearby areas of the brain or spinal cord. Sometimes they are called high-grade.

A benign brain tumour can change over time and become malignant.

The types of brain tumour that are most likely to affect teenagers and young adults are:

  • gliomas, which develop from supporting cells (glial cells) in the brain or spinal cord
  • pituitary area tumours, which grow in or near the pituitary gland
  • medulloblastomas, which start near the cerebellum at the back of the brain
  • germ cell tumours of the brain, which develop from germ cells sometimes found in the brain.

About this section

This section is for teenagers and young adults. It is about the brain and primary brain tumours. Primary brain tumours are tumours that start in the brain.

Any illness related to your brain can be scary. You might find it helpful to know a bit about how the brain works. Your doctor and specialist nurse can give you more information and answer any questions. If there is something you do not understand, don’t be scared to ask.

We have more information written for people of all ages about:


The brain and spinal cord

The brain and spinal cord together are called the central nervous system. The brain controls how we think, feel, learn and move. It also controls other important things, such as breathing and heart rate. It is inside the skull, which protects it.

The spinal cord is a long bundle of nerves that runs down the middle of the spine. These nerves pass messages between the brain and the rest of the body. The bones of the spine protect the spinal cord.

The brain and spinal cord
The brain and spinal cord

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Three thin layers of tissue cover the brain and spinal cord. These are called the meninges. Between two of these layers is a fluid called cerebrospinal fluid (CSF). The meninges and CSF also help to protect the brain and spinal cord.


The main parts of the brain

Different parts of the brain do different things. The main parts of the brain are the:

  • cerebrum
  • pituitary gland
  • cerebellum
  • brain stem
  • cranial nerves.

Side view of the brain
Side view of the brain

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Cerebrum 

This is the largest part of the brain and has two halves (hemispheres). 

The cerebrum controls: 

  • thinking
  • memory
  • behaviour
  • personality
  • movement
  • sensation. 

The right half of the cerebrum controls movement and sensation in the left side of the body. The left half of the cerebrum controls the right side of the body. It also controls speech.

Pituitary gland 

The pituitary gland is behind the nose and just below the base of the brain. It makes hormones (chemical messengers) that help control many processes in the body, including: 

  • how the body grows and develops from a child into an adult
  • how the body uses energy from food
  • water levels in the body
  • monthly menstrual periods 
  • making sperm. 

Cerebellum 

This is the area below the cerebrum, at the back of the brain. It controls balance and co-ordination.

Brain stem 

The brain stem is at the bottom of the brain and connects to the spinal cord. It controls important bodily functions that keep us alive. These functions include breathing, heart rate, blood pressure and body temperature. The brain stem also controls movements of the eyes and face, speech and swallowing.

Cranial nerves

These are nerves that go from the brain and brain stem to the eyes, nose, ears, tongue, face and shoulders. They carry messages from these areas about sensations such as taste, smell, vision and hearing. They also carry messages to the muscles that control eye and face movements, speech and swallowing.


Benign and malignant brain tumours

Brain tumours can be either benign (not cancer) or malignant (cancer). This information is about both types.

Benign brain tumours usually grow slowly. They might not cause symptoms for a long time. They are very unlikely to spread into other parts of the brain. But they can cause problems as they grow and press on nearby areas of the brain. Some benign brain tumours do not come back after treatment. But other brain tumours can come back and need further treatment. Sometimes, a benign brain tumour can change over time and become malignant.

Malignant brain tumours grow faster than benign tumours. They cause problems by spreading into and damaging nearby areas of the brain. Some tumours may spread to other parts of the brain or to the spinal cord. They rarely spread to other parts of the body. Malignant brain tumours are more likely to come back after treatment.

Grades of brain tumour

For some types of brain tumour, your doctor may talk about their grade.

The grade depends on how the cells look under a microscope. The grade may affect how slowly or quickly a tumour grows:

  • In grades 1 and 2, tumours are low-grade and benign and usually grow slowly.
  • In grades 3 and 4, tumours are high-grade and malignant (cancer) and usually grow more quickly.


Types of primary brain tumours

There are different types of brain tumour. They are usually named after the type of cell they develop from. Or sometimes they are named after the part of the brain they start in. The types of brain tumour that are most likely to affect teenagers and young adults are: 

  • gliomas
  • pituitary area tumours
  • medulloblastomas
  • germ cell tumours of the brain. 

However, other types of brain tumour can also affect teenagers and young adults. Your doctor can give you more information about these. 

Gliomas 

Gliomas develop from supporting cells (glial cells) in the brain or spinal cord. There are different types. They get their name from the type of glial cell they develop from: 

  • Astrocytoma is the most common glioma. It develops from a glial cell called an astrocyte.
  • Oligodendroglioma develops from a glial cell called an oligodendrocyte.
  • Ependymoma develops from a glial cell called an ependymal cell. They line the fluid-filled spaces in the brain (ventricles) and the centre of the spinal cord.

All these tumours can be benign or malignant (cancer).

Pituitary area tumours

Tumours that grow in or near the pituitary gland are usually benign and slow-growing. They can affect how the pituitary gland produces hormones. They can also affect vision. The most common types are pituitary adenomas and craniopharyngiomas. 

Medulloblastomas 

This type of cancer usually starts near the cerebellum at the back of the brain. Sometimes, medulloblastomas can spread to other parts of the brain or spinal cord. Or rarely they can spread to other parts of the body. 

Germ cell tumours of the brain 

These tumours develop from germ cells which are mainly in the ovaries or the testicles. Sometimes, there are small areas of germ cells in other parts of the body, such as the brain. Rarely, this results in germ cell tumours starting in the brain. 

Germ cell tumours can be benign or malignant (cancer). The two main types of germ cell brain tumours are germinomas and non-germinomas. Your team may check samples of your blood or CSF for higher than normal levels of certain chemicals. These are released by some types of germ cell tumour, so can help your team diagnose and monitor the tumour.  

Our general primary brain tumour section has more information that is written for all ages. The Children’s Cancer and Leukaemia Group has information about brain tumours in children.

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