Risks and causes of brain tumours

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

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.

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

Your risk of developing cancer depends on many things including your age, genetics, lifestyle and environmental factors. Anything that can increase your risk is called a risk factor.

The risk factors for developing a brain tumour include getting older and family history. But having a risk factor doesn’t mean that you will definitely develop a brain tumour.


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.

In particular, there is no evidence that brain tumours are caused by a head injury or a bump on the head. 

Last reviewed: 
29 Oct 2019
  • Brain, other CNS and intracranial tumours risk factors
    Cancer Research UK (Cancer Stats). Last accessed December 2018

  • The fraction of cancer attributable to modifiable risk factors in England, Wales, Scotland, Northern Ireland, and the United Kingdom in 2015
    K Brown and others
    British Journal of Cancer, 2018. Vol 118, pages 1130-1141

  • List of classifications by cancer sites with sufficient or limited evidence in humans, Volumes 1 to 123
    International Agency for Research on Cancer (IARC), Last accessed March 2013

  • Obesity and Risk for Brain/CNS Tumors, Gliomas and Meningiomas: A Meta-Analysis
    T Sergentanis and others
    PLoS One, 2015. Vol 10, Issue 9

  • Familial risks in nervous system tumours: joint Nordic study
    K Hemminki and others
    British Journal of Cancer, 2010. Vol 102, Pages 1786-1790

  • Epidemiology of primary brain tumors: Current concepts and review of the literature
    M Wrensch and others
    Neuro Oncology, 2002. Vol 4, Pages 278-299

Related links