A brain tumour is a collection of cells that have grown in a non ordered way. Tumours that start in the brain are called primary brain tumours.
This is different to cancers that have spread to the brain from somewhere else in the body. These are called secondary brain tumours or brain metastases.
Cancerous or non cancerous brain tumours
Generally, brain tumours can be cancerous (malignant) or non cancerous (benign).
Around half of all brain tumours, or tumours in another part of the central nervous system, are malignant. The other half are benign tumours, or tumours where the diagnosis is not known.
When the diagnosis is not known it is usually because the tumour is in a part of the brain that is too difficult to take a sample (biopsy) from.
Who gets it
Having a brain tumour is relatively rare. Brain tumours are more common in older people. Around 25 out of 100 (around 25%) of brain tumours in the UK each year are diagnosed in people aged 75 or older. This includes tumours in other parts of the central nervous system and tumours anywhere else inside the bones of the head.
Your brain controls your body by sending electrical messages along nerve fibres. The fibres run out of the brain and join together to make your spinal cord. Together your brain and spinal cord make your central nervous system (CNS).
The main areas of the brain include:
- The cerebrum (forebrain)
- The brain stem
- The cerebellum
The cerebrum is the largest part of the brain. It's also called the forebrain. It's divided into two halves, the right and left central hemispheres.
The nerves that come from the right side of your brain control the left side of your body. And the nerves that control the left side of your brain control the right side of your body.
Each half (central hemisphere) is divided into 4 areas.
The frontal lobe is important for:
- problem solving
- starting some movements
- processing sensations
- part of your personality and character
The temporal lobe is where you process sounds and where memories are stored.
The parietal lobe recognises objects in the world and stores that knowledge. It's where you receive and process:
This lobe processes what you can see.
The brain stem
This controls body functions we don't usually think about like:
- heartbeat and blood pressure
The cerebellum or hindbrain controls balance and posture. It is also involved with the timing and coordination of skilled movement.
Your brain makes hormones, which are important for your body to function.
Pituitary gland hormones
- the speed of body processes (your metabolism)
- periods and egg production
- sperm production
Pineal gland hormone
The pineal gland makes melatonin, which controls your sleep patterns.
Fluid around the brain
The brain and spinal cord are surrounded by fluid called cerebrospinal fluid (CSF).
Ventricles are spaces inside the brain filled with CSF. They connect with the space in the centre of the spinal cord and the brain covering. So the fluid can circulate around and through the brain and spinal cord.
Where it starts
Brain tumours can start anywhere in the brain.
They cause different symptoms depending on their position in the brain.
- if you have weakness on your left side, the tumour is in the right side of your brain
- a tumour in the parietal lobe can affect speech, reading or writing
- a tumour in the occipital lobe can cause sight problems
- a tumour in the cerebellum can affect balance and movement
How common it is
There were around 11,400 people diagnosed with a brain tumour in the UK in 2015. This includes tumours in other parts of the central nervous system and tumours anywhere else inside the bones of the head.
The number of people diagnosed with brain tumours in the UK is increasing. This is thought to be mainly because health professionals are getting better at:
- diagnosing brain tumours
- recording a brain tumour diagnosis