Risks and causes of brain tumours

What is a risk factor?

Anything that increases your risk of getting cancer is a risk factor. Having a risk factor does not mean you will get cancer.

What are the risk factors for brain tumours?

Age is a risk factor in brain tumours. The older you get the higher the risk. Being overweight or obese can also slightly increase your risk.

If you have had radiotherapy treatment before can also increase your risk slightly. As can having a close relative such as parent, child or sibling who has had a brain tumour.

Can I reduce my risk?

There are ways you can reduce your risk of cancer in general.


Brain tumours can start at any age. But as we get older our risk of developing most cancers, including brain tumours, increases.

The risk of brain tumours is greatest in those aged between 85 and 89 years.

Overweight and obesity

Being overweight or obese increases the risk of some cancer types, including a type of brain tumour called meningioma. About 2 out of 100 brain tumours (2%) diagnosed in the UK every year are caused by being overweight or obese.

Try to keep a healthy weight by keeping physically active and eating a healthy, balanced diet.

Medical radiation (ionising radiation)

Ionising radiation is a type of radiation used by some medical scans, such as x-rays and CT scans. These scans are important to help diagnose many illnesses, including cancer.

Less than 1 out of every 100 brain tumours (less than 1%) diagnosed in the UK are caused by ionising radiation. Most cases happen in people who have received radiation from previous radiotherapy treatments, rather than from x-rays and CT scans.

The risks of radiation from medical scans are very low. Your doctors and dentist will keep your exposure to radiation as low as possible. They will only do x-rays and CT scans when they are necessary.

Family history and genetic conditions

Your risk is higher than other people in the general population if you have a close relative who has had a brain tumour. A close relative is a parent, sibling or child.

A small proportion of brain tumours are related to known genetic conditions. People who have one of these rare syndromes have an increased risk of getting a brain tumour.

These syndromes include:

  • neurofibromatosis (NF) type 1 and type 2
  • tuberous sclerosis (TSC)
  • Li-Fraumeni syndrome
  • Von Hippel-Lindau syndrome (VHL)
  • Turner syndrome
  • Turcot syndrome
  • Gorlin syndrome

For detailed information on brain tumours risks and causes

Reducing your risk

There are ways you can reduce your risk of cancer in general. 

Cancer myths

Stories about potential causes are often in the media and it isn’t always clear which ideas are supported by evidence. There might be things you have heard of that we haven’t included here. This is because either there is no evidence about them or it is less clear.

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  • Body Fatness and Cancer--Viewpoint of the IARC Working Group
    B Lauby-Secretan and others
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  • Familial risks in nervous system tumours: joint Nordic study
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  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. If you need additional references for this information please contact patientinformation@cancer.org.uk with details of the particular risk or cause you are interested in. 

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

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