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Brain tumour risks and causes

Brain tumours are relatively rare. In most cases, we don't know what causes a brain tumour. But there are a few risk factors we do know about.

Age

People can get brain tumours at any age. Like most cancers, they are more common the older you get. But some specific types are more common in younger people. Only about 400 children are diagnosed with brain tumours in Great Britain each year. But brain tumours are still the second most common type of cancer in children, after leukaemia.

Other risk factors

A small proportion of brain tumours are related to genetic conditions. If you have a parent, brother or sister diagnosed with a brain tumour, your risk is higher compared to the general population. People with HIV or AIDS are also at increased risk.

Exposure to radiation is a definite risk factor for brain tumours. Some types of brain tumour are more common in people who have had radiotherapy, CT scans or X-rays to the head in the past. Researchers have investigated many other possible risk factors, but none of these have been proven.
 

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How common brain tumours are

In most cases, we do not know what causes a brain tumour. We do know that they are not infectious. You can't catch a brain tumour. There are a few risk factors that we do know about.

Brain tumours are relatively rare. In the UK, around 9,400 people are diagnosed each year with a tumour that started in the brain, or elsewhere in the central nervous system (CNS) or within the skull (cranium). We call all of these brain tumours on this page. Around half of these people have cancerous (malignant) brain tumours. The other half have non cancerous (benign) tumours, or tumours which have not been confirmed as either cancerous or non cancerous. This is usually because the tumour is in an area of the brain or CNS that is too difficult to take samples (biopsies) from to make the diagnosis.

Cancerous brain tumours are more common in males than females. Non cancerous brain tumours, and tumours where the diagnosis is unknown, are more common in females.

 

Age

People can get brain tumours at any age. Generally speaking, as we get older our risk of brain tumours increases. But there are many different types of brain tumours and some are more common in younger adults. Overall, more brain tumours are diagnosed now than in the 1970s. This increase in rates is thought to be mainly because we are getting better at diagnosing and collecting data on brain tumours.

Around 400 children (under age 15) are diagnosed with brain tumours in Great Britain each year, so they are quite rare. But brain tumours are the 2nd most common type of cancer in children.

Around 300 teenagers and young adults (aged 15 to 24) are diagnosed with brain tumours in the UK each year. They are the 4th most common type of cancer in this age group.

 

Medical radiation

Exposure to radiation is the only definite risk factor we know about. Types of brain tumours called meningiomas and, to a lesser extent, cancerous (malignant) gliomas, are more common in people who have had radiotherapy, CT scans or X-rays to the head. It is important to remember that X-rays and CT scans are very important in diagnosing illness so that you have the right treatment. Doctors keep medical exposure to radiation as low as possible.

 

Previous cancers

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 or non Hodgkin lymphoma 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 may be due to the treatment for the previous cancer, such as radiotherapy to the head. Giving the cancer drug methotrexate into the fluid around the spinal cord (intrathecal methotrexate) for the treatment of leukaemia has been shown to increase the risk of brain tumours. It is important to remember that any increase in brain tumour risk from cancer treatment is small compared to the risk of not having the treatment for the original cancer.

 

Genetic conditions and family history

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 cause a number of different medical problems, and so you may already know if any of these run in your family. Examples are 

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

 

Other medical conditions and medicines

People with HIV or Aids have around double the risk of being diagnosed with a brain tumour compared to the general population.

Post menopausal women who are taking hormone replacement therapy (HRT) may have a slightly increased risk of developing meningioma compared with women who have never taken HRT. Women taking oral contraceptives might also have a higher risk of meningioma but more research is needed to confirm this link.

 

Body size and exercise

Being overweight (having a larger waist size or greater body mass index – BMI) gives a slightly higher risk of meningioma than in smaller people. But being overweight doesn't seem to affect glioma risk.

Children weighing 4kg or more at birth have a small increased risk of some brain tumour types compared with lighter babies.

Taller people might have an increased risk but the evidence on this is still mixed.

Studies that look at food and drink in relation to brain tumour risk are not felt to be reliable. This is because brain tumours are relatively rare and measuring diet accurately is very difficult. People who are very physically active might reduce their brain tumour risk but the evidence is mixed.

 

Other possible risk factors

Research has looked at other factors that my increase brain tumour risk, including 

Power lines

Several studies have looked at whether living near power lines increases the risk of brain tumours but they have not found an increased risk. There is detailed information about research on power lines and cancer in the healthy living section of the website.

Mobile phones

Researchers are investigating mobile phones to see how much low level (non ionising) radiation they produce. From the evidence so far we still can't say that mobile phones pose a problem to health. There has been a concern about them causing brain tumours in particular. But there is no strong evidence that there is any link. There is information about research into mobile phones and brain tumours in the healthy living section of the website.

Hair dye

According to the latest research, using hair dye is unlikely to increase your risk of developing a brain tumour.

Smoking and alcohol

It's not yet clear whether smoking affects brain tumour risk. But some studies have shown increased risks for some types of brain tumour. Drinking alcohol doesn't seem to affect risk.

 

Factors that may reduce risk

There is some evidence that people with allergies such as eczema, asthma and hayfever may have a slightly reduced risk of brain tumours, particularly gliomas. This might be related to an increase in immune system activity.

Aspirin and other anti inflammatory drugs probably do not affect brain tumour risk. Some trials have found a slight decrease in risk. But these trials weren't designed to look specifically at brain tumour risk and so more research is needed. Remember that aspirin can be dangerous because it can irritate the stomach lining and cause bleeding. You should not start to take aspirin or other anti inflammatory drugs without checking with your doctor first.

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Updated: 14 January 2014