What are brain tumours?

A brain tumour is a collection of brain cells that have grown out of control.

Our body is made up of billions of cells that can only be seen under a microscope. Normally, cells only divide to replace old and worn out cells. A brain tumour develops when something inside a cell goes wrong, making the cell carry on dividing until it forms a lump or a tumour.

Tumours that start in the brain are called primary brain tumours.

This is different from cancers that have spread to the brain from somewhere else in the body. These are called secondary brain cancers or brain metastases. The information on this page is about primary brain tumours.  

The brain is made of different tissues and cells which can develop into different types of tumours. There are over 100 different types of brain tumours.

Cancerous or non cancerous brain tumours

Generally, brain tumours can be benign (non cancerous) or malignant (cancerous).

Benign brain tumours

Benign tumours usually grow slowly. They are less likely to come back after treatment or to spread to other parts of the brain. Your doctor might refer to some benign brain tumours as low grade.

Each year around 6,500 people are diagnosed with a benign or an uncertain or unknown behaviour brain tumour in the UK. An uncertain or unknown behaviour tumour means that doctors can't tell how the tumour will behave.

Malignant brain tumours

Malignant brain tumours grow faster than benign tumours. They are more likely to come back after treatment and to spread to other parts of the brain. Your doctor might refer to malignant brain tumours as high grade.

Each year around 5,800 people are diagnosed with a malignant brain tumour in the UK.

The brain and spinal cord

The brain and the spinal cord make up the central nervous system (CNS). The CNS is made up of different types of cells and tissues. Brain tumours are usually named after the cell or tissue they started in. 

Diagram showing spinal cord and the brain
Brain tumours can start anywhere in the brain. They cause different symptoms depending on their position in the brain. Tumours can also start in the spinal cord.

How common is it?

Primary brain tumours are relatively rare. Around 12,300 people are diagnosed with a brain tumour in the UK each year. This includes tumours in other parts of the central nervous system such as the:

  • spinal cord
  • covering of the brain (meninges) 
  • nerves leading from the brain

Who gets it?

Brain tumours are more common in older people. Almost 25 out of every 100 people (almost 25%) diagnosed with a brain or spinal cord tumour in the UK every year are aged 75 or older.

Tumours affecting the brain and spinal cord are the second most common type of children’s cancer in the UK.

  • Cancer Incidence from Cancer Intelligence Statistical Information Team at Cancer Research UK  (2016 - 2018 UK average) 
    Accessed January 2023

  • Ross and Wilson Anatomy and Physiology in Health and Illness (14th edition)
    A Waugh and A Grant
    Elsevier Health Sciences, 2022

  • Cancer and its Management (7th edition)
    J Tobias and D Hochhauser
    Wiley-Blackwell, 2014

  • Brain tumours (primary) and brain metastases in adults
    National Institute for Health and Care Excellence (NICE), 2018

  • The 2021 World Health Organization Classification of Tumors of the Central Nervous System: a summary
    D Louis and others
    Neuro-oncology, 2021, Vol 23, Issue 8, Pages 1231-1251

Last reviewed: 
18 Jan 2023
Next review due: 
18 Jan 2026

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