What is a tumour?
A tumour is any abnormal group of cells. It is also called a growth or neoplasm. Brain tumours are a rare but serious condition in children.
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.
A cell can become abnormal when genes in cells change or are missing. As a result, the cell's "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.
How does the health-care team know that a child 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 infants. The bones in their heads have not yet joined together. As a result, these bones spread apart as the tumour grows. In infants, the only symptom of a tumour may be that the size of their head is bigger than other infants their age.
In general, the signs and symptoms depend on the type of tumour, its location, and its size.
What are signs and symptoms of a brain tumour?
The symptoms of a brain tumour depend on where the tumour is located in the brain. Some common symptoms that brain tumours cause include:
- headaches, caused by increased pressure on the brain
- vomiting or nausea, caused by increased pressure on the brain
- vision problems (e.g., double vision, blurred vision)
- lack of coordination (e.g., ataxia, dysmetria)
- handwriting and school performance gradually get worse
- seizures
- weakness or loss of feeling in parts of the body
- changes to the senses of hearing or smelling
- changes in personality or memory
In infants, some of the symptoms are:
- irritability
- sleepiness
- changes in sleep patterns
- crying more than usual
- falling behind in meeting developmental milestones
- unusual growth in head size
- lack of coordination
Vision problems
In some cases, the tumour affects the optic nerve. This is a nerve that carries messages between the eye and the brain. It may also affect the cranial nerves, which control the movement of the eyes. Vision problems caused by a brain tumour include:
- papilledema (swelling of the optic nerve, which connects the eye and the brain)
- vision loss
- double vision
- nystagmus (rapid, uncontrollable eye movement)
- tunnel vision
- blindness
Lack of coordination
A brain tumour can create coordination problems. Lack of coordination is associated mostly with tumours in the cerebellum and brain stem. Two of the signs that are associated with brain tumours are:
- Ataxia: A child with ataxia has clumsy movements and is unsteady on their feet. They may frequently fall down or have problems sitting up without support.
- Dysmetria: This occurs when a child cannot accurately control an action. For example, when reaching for a book, they may not be able to judge how far they should move their hand to get the book, or the strength they need to pick it up. They may also be unable to control the speed at which they move their hand.
What causes brain tumours?
It is not known 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.
However, there are a few known reasons why some cells become abnormal and form a tumour. First, there are certain medical conditions in families that make a child more likely to have abnormal cells. Second, as a child is developing, things can go wrong with cells by chance.
What are the medical conditions connected to brain tumours?
Having certain genetic conditions may result in a slightly higher chance that your child or others in the family will develop a brain tumour. These conditions account for up to 10% of childhood brain tumours. These medical conditions include:
- Neurofibromatosis
- Tuberous sclerosis
- Von Hippel-Lindau disease
- Li-Fraumeni syndrome
- Lynch syndrome
- Constitutional mismatch repair deficiency or cMMRD
- 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. There is currently no evidence to suggest a link between brain tumours and mother’s diet during pregnancy, child’s diet, pesticides or viruses.
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.
Radiation
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.
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 leukemia.
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 first bring your child to their primary care provider after they experience some symptoms. Once the care provider determines that more common illnesses cannot explain these symptoms, they may refer your child to a specialist.
A neurologist, or neurosurgeon, and other health-care professionals will use well-established diagnostic procedures, such as brain imaging, to see if a brain tumour is causing the symptoms. If the symptoms are dramatic, the diagnosis may happen quicker. If they are milder, it can take several months. There have been many studies that have looked at the time between initial symptoms and the diagnosis. The hypothesis was that the sooner the diagnosis, the better the treatment outcome. In fact, most studies have shown the opposite. This suggests that more aggressive tumours tend to be diagnosed earlier.
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 two or three types. All the health-care professionals involved in your child’s care will meet to decide on a treatment plan.