Childhood Visual Pathway Glioma

What is childhood visual pathway glioma?

Childhood visual pathway glioma is a type of brain tumour in which cancer (malignant) cells begin to grow in the tissues of the brain. The brain controls memory and learning, the senses (hearing, sight, smell, taste, and touch), and emotion. It also controls other parts of the body, including muscles, organs, and blood vessels. Other than leukaemia or lymphoma, brain tumours are the most common type of cancer that occurs in children.

Gliomas are a type of astrocytoma, tumours that start in brain cells called astrocytes. A visual pathway glioma occurs along the nerve that sends messages from the eye to the brain (the optic nerve). Visual pathway gliomas are visual pathway tumours. They may grow rapidly or slowly, depending on the grade of the tumour.

This summary covers tumours that start in the brain (primary brain tumours). Often cancer found in the brain has started somewhere else in the body and has spread (metastasized) to the brain. This is called brain metastasis (refer to the summary on Adult Brain Tumours Treatment for more information).

Like most cancer, childhood brain tumour is best treated when it is found (diagnosed) early. If your child has symptoms, the doctor may order a computed tomographic (CT) scan, a special x-ray that uses a computer to make a picture of your child’s brain. A magnetic resonance imaging (MRI) scan, which uses magnetic waves to make a picture of your child’s brain, may also be done.

Often, surgery is required to see whether there is a brain tumour and to tell what type of tumour it is. The doctor may cut out a piece of tissue from the brain and look at it under a microscope. This is called a biopsy.

There are many types of brain tumours in children and the chance of recovery (prognosis) depends on the type of tumour, where it is located within the brain, and your child’s age and general health.

Stage Explanation

Once childhood visual pathway glioma is found, more tests will be done to find out the type of tumour. If a biopsy specimen is taken, the cancer cells will be looked at carefully under a microscope to see how different they are from the normal cells. This will determine the histologic grade of the tumour. Your child’s doctor needs to know the type and grade of tumour in order to plan treatment.

There is no staging for childhood visual pathway glioma. The treatment depends on whether or not your child has received treatment.
Untreated childhood visual pathway glioma

Untreated childhood visual pathway glioma means that no treatment has been given except to treat symptoms.
Recurrent visual pathway glioma

Recurrent disease means that the cancer has come back (recurred) after it has been treated. It may come back in the brain or in the head or spinal area.

Treatment Option Overview

There are treatments for all children with visual pathway glioma. Three kinds of treatment are used:

* Surgery (taking out the cancer in an operation).

* Radiation therapy (using high-dose x-rays to kill cancer cells).

* Chemotherapy (using drugs to kill cancer cells).

Experienced doctors working together can often give the best treatment for children with visual pathway glioma. Your child’s treatment will often be coordinated by a paediatric oncologist, a doctor who specializes in cancer in children. The paediatric oncologist may refer you to other doctors, such as a paediatric neurosurgeon (a specialist in childhood brain surgery), a paediatric neurologist, a psychologist, a radiation oncologist, and other doctors who specialize in the type of treatment your child requires.

Surgery is one treatment for visual pathway glioma. Depending on where the cancer is and the type of cancer, your child’s doctor may remove as much of the tumour as possible. If the tumour cannot be totally removed, radiation therapy and chemotherapy may also be given. If the cancer is in a place where it cannot be removed, surgery may be limited to a biopsy of the cancer.

Radiation therapy uses high-energy x-rays to kill cancer cells and shrink tumours. Radiation therapy for childhood brain tumours usually comes from a machine outside the body (external radiation therapy). Because radiation therapy can affect growth and brain development, clinical trials are testing ways to decrease or delay radiation therapy, especially for younger children. These include internal radiation therapy, in which radiation is put into the brain through thin plastic tubes, and hyperfractionated radiation therapy, in which radiation therapy is given in several small doses per day instead of all at once. Conformal radiation therapy uses a computer to create a 3-D picture of the tumour and the radiation beams are shaped to fit the tumour; this helps to keep the radiation away from healthy tissue as much as possible.

Chemotherapy uses drugs to kill cancer cells. Chemotherapy may be taken by pill, or it may be put into the body by a needle in a vein or muscle. Chemotherapy is called a systemic treatment because the drug enters the bloodstream, travels through the body, and can kill cancer cells throughout the body. Chemotherapy is being studied to delay the use of radiation therapy in some patients. Clinical trials are studying different chemotherapy drugs for visual pathway gliomas.

Some cancer treatments cause side effects that continue or appear years after cancer treatment has ended. These are called late effects. Late effects of cancer treatment may include physical problems; changes in mood, feelings, thinking, learning or memory; and having second cancers (new types of cancer). Some late effects may be treated or controlled. It is important to talk with your child's doctors about the possible late effects caused by some treatments. Refer to the summary on Late Effects of Treatment for Childhood Cancer for more information.
Treatment by type

Treatment for childhood visual pathway glioma depends on the type and stage of the disease and your child’s age and overall health.

Your child may receive treatment that is considered standard based on its effectiveness in a number of patients in past studies, or you may choose to have your child go into a clinical trial. Not all patients are cured with standard therapy and some standard treatments may have unwanted side effects. For these reasons, clinical trials are designed to test new treatments and to find better ways to treat cancer patients. Clinical trials are going on in most parts of the country for childhood visual pathway glioma.

Untreated Childhood Visual Pathway Glioma

Your child’s treatment may be one of the following:

1. For patients without symptoms or progression, observation without treatment.
2. Surgery.
3. Radiation therapy.
4. Chemotherapy.
5. Clinical trials evaluating chemotherapy to shrink the tumour and delay radiation therapy.

Recurrent Childhood Visual Pathway Glioma

Treatment for recurrent disease depends on the type of tumour, whether the tumour comes back in the same place or in another part of the brain, and the treatment that was given before.

If possible, the tumour may be removed during surgery. Radiation therapy may be given, especially if it was not given before. Chemotherapy may be used, and clinical trials are evaluating new chemotherapy drugs. You may wish to consider having your child treated with new methods on a clinical trial.