This information is about a specific type of brain tumour called an oligodendroglioma. It should ideally be read with our general information about brain tumours.

The central nervous system (CNS), is made up of the brain and spinal cord. Cells in the CNS normally grow in an orderly and controlled way, but if for some reason this order is disrupted, the cells continue to divide and form a lump or tumour.

A tumour may be either benign or malignant. Although a benign tumour can continue to grow, the cells do not spread from the original site. In a malignant tumour, the cells can invade and destroy surrounding tissue and may spread to other parts of the brain.

Tumours affecting the CNS are fairly rare. About 4500 people are diagnosed with tumours of the CNS each year in the UK. Many of these tumours are malignant.

Within the brain there are nerve cells, and also cells that support and protect the nerve cells. The supporting cells are called glial cells. A tumour of these cells is known as a glioma.

Oligodendroglioma is a type of glioma and develops from cells called oligodendrocytes. These cells produce the fatty covering of nerve cells. This type of tumour is normally found in the cerebrum (the white area on the diagram made up of the four lobes), particularly in the frontal or temporal lobes.

Oligodendrogliomas are divided into two types:

• a well-differentiated tumour, which grows slowly
• an anaplastic oligodendroglioma, which grows more quickly.

Although this type of tumour is more common in adults, it can occur in children. For unknown reasons, it is more common in men than in women.

Oligodendrogliomas may be graded from 1–4, depending on how abnormal the cells are and how quickly they are growing. Grade 1 is the least malignant and grade 4 is the most. Grade 1 and 2 oligodendrogliomas may be referred to as low-grade tumours, and grade 3 and 4 as high-grade.

As with most brain tumours, the cause of oligodendroglioma is unknown. Research is being carried out into possible causes.

People with slow-growing oligodendrogliomas may have mild symptoms for several years before the tumour is discovered.

The first symptoms of any type of brain tumour are usually due to increased pressure within the skull (raised intracranial pressure). This may be caused by a blockage in the ventricles (fluid-filled spaces of the brain) which leads to a build-up of cerebrospinal fluid (CSF). CSF is the fluid that surrounds the brain and the spinal cord. This increased pressure may also be caused by swelling around the tumour itself.

Raised intracranial pressure can cause headaches, sickness (vomiting) and visual problems. Fits (seizures) and changes in behaviour and personality can also be general signs of a brain tumour.

Oligodendrogliomas can grow in different parts of the brain, and symptoms may relate to the area of the brain which is affected:

• A tumour of the frontal lobe of the brain may cause gradual changes in mood and personality. There may also be paralysis on one side of the body (hemiparesis).
• A tumour in the temporal lobe of the brain may cause problems with coordination and speech, and may affect your memory.

So that your doctors can plan your treatment, they need to find out as much as possible about the type, position and size of the tumour, so you may have a number of tests and investigations.

Neurological examination (nerve tests) This will assess any effect of the tumour on your nervous system.

CT (computerised tomography) scan A CT scan takes a series of x-rays which build up a three-dimensional picture of the inside of the body. The scan is painless and takes from 10–30 minutes. CT scans use a small amount of radiation, which will be very unlikely to harm you and will not harm anyone you come into contact with. You will be asked not to eat or drink for at least four hours before the scan. A CT scan may be used to identify exactly where the tumour is or to check for any spread of the cancer.

Most people who have a CT scan are given a drink or injection to allow particular areas to be seen more clearly. This may make you feel hot all over. Before having the injection or drink, it is important to tell the person doing this test if you are allergic to iodine or have asthma.

MRI (magnetic resonance imaging) scan This test is similar to a CT scan, but uses magnetism instead of x-rays to build up a detailed picture of areas of your body. During the scan you will be asked to lie very still on a couch inside a long tube for about 30 minutes. It is painless but can be uncomfortable, and some people feel a bit claustrophobic during the scan. It is also noisy, but you will be given earplugs or headphones to wear.

Some people are given an injection of dye into a vein in the arm, but this usually does not cause any discomfort.

Biopsy To give an exact diagnosis, a sample of cells from the tumour is sometimes taken, then looked at under a microscope. The biopsy involves an operation. Your doctor will discuss with you whether this is necessary in your case, and what the operation involves.

The treatment for oligodendroglioma depends on a number of things, including your general health, the size and position of the tumour, and whether it has spread to surrounding areas. The results of your tests will enable your doctor to discuss your treatment plan with you.

Your treatment will usually be planned by a team of specialists known as a multidisciplinary team (MDT). The team will usually include a doctor who operates on the brain (neurosurgeon), a doctor who specialises in treating illnesses of the brain (neurologist), a doctor who specialises in treating cancer (an oncologist), a specialist nurse and possibly other health professionals, such as a physiotherapist or a dietitian.

There are some risks associated with treatment to the brain and your doctor will also discuss these with you.

If the pressure in the skull is raised, it is important to reduce it before any treatment is given for brain tumours. Steroid drugs may be used to reduce swelling around the tumour. If raised intracranial pressure is due to a build-up of CSF, a tube (shunt) may have to be inserted to drain off the excess fluid.

Surgery

Where possible, surgery is the main treatment for oligodendroglioma. The aim of surgery is to remove as much of the tumour as possible without damaging the surrounding brain tissue. Depending on the size and position of the tumour, it may not be possible to remove it completely and further treatment may be given after the surgery.

Some tumours cannot be reached by surgery, or the risk of damage to the rest of the brain may be too high. If surgery is not possible, your doctor will discuss other types of treatment with you.

Radiotherapy

Radiotherapy treatment is the use of high-energy rays to destroy cancer cells and is often used after surgery. The aim of the radiotherapy is to destroy any remaining malignant cells. It may be used on its own to treat oligodendroglioma if surgery is not possible.

Radiotherapy is usually given as an external treatment, but occasionally it may be given in the form of radioactive implants (small radioactive metal objects which are inserted into the tumour during an operation).

Chemotherapy

Chemotherapy is the use of anti-cancer (cytotoxic) drugs destroy cancer cells. It may be given alone, or together with surgery and/or radiotherapy to treat oligodendroglioma.

You may find the idea of a tumour affecting your brain extremely frightening. The brain controls the body, and not being in control is something that can be very worrying. You may experience many different emotions, including anxiety and fear. These are all normal reactions, and are part of the process many people go through in trying to come to terms with their condition.

Many people find it helpful to talk things over with their doctor or nurse, or with one of our support service nurses. Close friends and family members can also offer support.

Driving

In some circumstances, you may not be allowed to drive for a period of time. If you have had an epileptic fit, the Drivers and Vehicle Licensing Association (DVLA) will not allow you to drive for a year after your last fit. You can then drive again provided you remain well.

After treatment, you will not be able to drive for at least one to two years, depending on the grade of your tumour. If the tumour comes back, however, this period will be extended.

You may not be allowed to drive some vehicles, such as a LGV (large goods vehicle) or a PCV (passenger carrying vehicle).

The hospital will not contact the DVLA, but it is your responsibility to do so and your doctor will advise you how to do this.

This section has been compiled using information from a number of reliable sources, including:

• Oxford Textbook of Oncology (2nd edition). Souhami et al. Oxford University Press, 2002.
• The Textbook of Uncommon Cancers (3rd edition). Raghavan et al. Wiley, 2006.
• Cancer in the Nervous System (2nd edition). Levin, Oxford University Press, 2002.

For further references, please see the general bibliography.