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Risks and causes of brain tumours

We don't know what causes most brain cancers. But there are some factors that may increase your risk of developing it. 

Anything that increases your risk of getting a disease is called a risk factor. Different cancers have different risk factors.

Having any of these risk factors does not mean that you will definitely develop a brain tumour.

Causes and risks

People can get brain tumours at any age. As we get older our risk of brain tumours increases. But there are many different types of brain tumour and some are more common in younger people.

Exposure to radiation is the only definate risk factor we know about. But it only accounts for a very small number of brain tumours.

There are many different types of brain tumours. Two types are:

  • meningiomas
  • cancerous (malignant) gliomas

These types are more common in people who have had radiotherapy, CT scans or x-rays to the head. Especially those who have had treatments and scans for childhood cancers.

X-rays and CT scans are very important in diagnosing illness so that you have the right treatment. Doctors and dentists keep medical exposure to radiation as low as possible. They are only done when are necessary.

People who have had cancer as a child have a higher risk of developing a brain tumour later in life. People who have had leukaemia, non Hodgkin lymphoma or a glioma brain tumour as an adult also have an increased risk.

There is some evidence that there is an increased risk of brain tumours in adults who have had other types of cancer but more research is needed to confirm this.

The increase in brain tumour risk might be due to the treatment for the previous cancer, such as radiotherapy to the head.

Having the chemotherapy drug methotrexate into the fluid around the spinal cord (intrathecal methotrexate) has been shown to increase the risk of brain tumours. Methotrexate is used to treat leukaemia, a type of blood cancer.

Your risk of getting a brain tumour is still small. You would be at a much higher risk from the cancer you are having treatment for if you don't have it.

Your risk is higher than other people in the general population if you have a parent, brother or sister diagnosed with a brain tumour.

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 type 1 and 2
  • tuberous sclerosis
  • Li-Fraumeni syndrome
  • Von Hippel-Lindau syndrome
  • Turner syndrome
  • Turcot syndrome
  • Gorlin syndrome

People with HIV or AIDS have around double the risk of being diagnosed with a brain tumour compared to the general population. This may be related to lowered immunity.

Being overweight or obese increases the risk of some types of brain cancer. Obesity means being very overweight with a body mass index (BMI) of 30 or higher. And being overweight is a BMI of between 25 and 30. 

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

Cancer controversies

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.

For detailed information on brain tumours risks and causes

Reducing your risk

There are ways you can reduce your risk of cancer.

Last reviewed: 
08 Aug 2016
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    MS Shiels and others
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    Journal of Clinical Oncology, 2010. Volume 28, Issue 36

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    Lancet Oncology, 2011. Volume 12, Issue 4

  • Risk of second benign brain tumors among cancer survivors in the surveillance, epidemiology, and end results program
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    Cancer Causes & Control, 2014. Volume 25, Issue 6

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