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Brain Tumours: An Overview

What is a tumour?

A tumour is any abnormal group of cells. It is also called a growth or neoplasm.

How common are brain tumours?

Brain tumours are rare in children. Each year in Canada, they affect about 300 children under the age of 18. Most occur in children aged five to eight. They are the second most common type of cancer in children, after leukaemia.

Normal Cell Division
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Genes are located in the centre of the cell, in the nucleus. Some genes control how cells make copies of themselves.

How do we know that someone has a brain tumour?

The brain contains the structures that direct everything we do, such as seeing, hearing, moving, thinking, and learning. These structures also control our emotions and ability to communicate. If a tumour grows in the brain, it can crowd these structures. This affects the child’s ability to function.

Because of its size, the tumour can also create pressure on the brain. This can cause symptoms such as headaches, vomiting, and nausea.

The situation is different in babies. The bones in their heads have not yet joined together. As a result, these bones can get bigger as the tumour grows. In babies, the only symptom of a tumour may be that the size of their head is bigger than other babies their age.

In general, the signs and symptoms depend on the type of tumour, its location, and its size.

For more information, please see " Signs & Symptoms."

Tumour Cell Division
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When genes in a cell change or are missing, cells can make copies of themselves in unpredictable and uncontrollable ways. Tumours may develop.

How do tumours form?

Normal cells are tiny building blocks of the body. Every cell contains genes. Our genes are like a “command centre” that tell our cells what to do.

We know that a cell can become abnormal when genes in cells change or are missing. As a result, the “command centre” doesn’t work properly. Abnormal cells begin to grow. These abnormal cells keep making copies of themselves. As the number of abnormal cells grows, they form a tumour.

What causes brain tumours?

We don’t know exactly what causes brain tumours to develop. There is no way to predict that a child will get a tumour. Nobody is to blame if a child develops a tumour.

We do know a few reasons why some cells become abnormal and form a tumour. First, there are certain medical conditions in families. They make a child more likely to have abnormal cells. Second, as a child is developing, things can go wrong with genes by chance. Researchers have also been studying whether environmental factors, such as radiation, food, or chemicals, can change genes.

What are the medical conditions connected to brain tumours?

If there are certain medical conditions in your family, that means that family members carry some genes that are not normal. You have some of the same genes as your family members. Therefore, it is possible that you might carry some of these genes that are not normal.

Having certain medical condtions may result in a slightly higher chance that you or others in the family will develop a brain tumour. These medical conditions include:

  • neurofibromatosis
  • tuberous sclerosis
  • von Hippel-Lindau disease
  • Li-Fraumeni syndrome
  • Gorlin syndrome
  • Turcot syndrome
  • Rubinstein-Taybi syndrome

Sometimes children are screened for brain tumours regularly if a family member has one of these conditions. However, it is rare to develop brain tumours even with these conditions.

What impact do environmental factors have on brain tumours?

Researchers have done many large studies to find out whether things in the environment, such as food or radiation, cause tumours. Here are some areas that they have studied.

The mother’s diet during pregnancy

At the moment, no link has been found between a mother’s diet while she was pregnant and brain tumours in her child. This means that hot dogs, cured meats, diet soft drinks, aspartame, or foods containing coloured dyes do not appear to cause brain tumours.

The child’s diet

At the moment, no link has been found between a child’s diet and brain tumours. This means that hot dogs, cured meats, diet soft drinks, aspartame, or foods containing coloured dyes do not appear to cause brain tumours.


At the moment, no link has been found between brain tumours and pesticides that are sprayed on vegetables, fruits, or lawns.

Chemical exposure at work

Brain tumours occur more often in people exposed to certain chemicals through their work. These chemicals include vinyl chloride, acrylonite, and formaldehyde. However, no link has been found between a parent’s contact with these chemicals and a child’s brain tumour.


Many people worry that power lines, household appliances such as microwaves, or cellular phones cause brain tumours. At the moment, there has been no definite proof that these types of radiation can cause brain tumours.

However, one type of radiation called high-dose ionizing radiation does cause cancer. This radiation is used to treat cancer, and it has been linked to second cancers in patients who have received this treatment in the past.


Researchers are investigating whether viruses may lead to brain tumours. There is no proof that they are linked at the moment.

How are brain tumours diagnosed?

The diagnosis of a brain tumour can be a long process. One reason is that brain tumours can cause many different problems. These problems, or symptoms, are often the same as symptoms of more common illnesses or injuries.

Typically, you would probably bring your child to her doctor first after she experiences some symptoms. Once the doctor realizes that more common illnesses cannot explain these symptoms, he will refer your child to a specialist.

A neurologist, or neurosurgeon, and other medical professionals will test your child using well-established diagnostic procedures to see if a brain tumour is causing the symptoms. If the symptoms are dramatic, the diagnosis may happen quickly. If they are milder, it can take several months.

For more information, please see " Understanding Diagnosis."

How are brain tumours treated?

The 3 types of treatment for brain tumours are surgery, chemotherapy, and radiation therapy.

The type of treatment is based on your child’s age, the location of the tumour, the type of tumour, and on how fast the tumour is growing. Some children need only one type of treatment. Others need 2 or 3 types. All the doctors involved in your child’s care will meet to decide on a treatment plan.

For more information, please see " Treatment of Brain Tumours."

Eric Bouffet, MD, FRCPC