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

Cells within the central nervous system (CNS), which is made up of the brain and spinal cord, 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. Just over 5000 new tumours are diagnosed each year in the UK. Many of these are malignant.

Most brain tumours are named after the cells from which they develop. 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.

Astrocytomas, ependymomas and oligodendrogliomas are all types of glioma. They are named after the cells from which they grow: astrocytes, ependymal cells and oligodendrocytes.

A mixed glioma is a malignant tumour that contains more than one of these cell types, for example, astrocytes and oligodendrocytes. This type of mixed glioma is referred to as an oligo-astrocytoma and shows characteristics of both these tumours.

The most common site for a mixed glioma is the cerebrum, the main part of the brain. Like other malignant tumours, it may spread to other parts of the brain (see diagram).

Although mixed gliomas are more common in adults, they can occur in children. For unknown reasons, they are more common in men than women.

Like other brain tumours, mixed gliomas are graded from 1–4, depending on how abnormal the cells are and their rate of growth. Grade 1 is the least malignant and grade 4 is the most. Grade 1 and 2 tumours may be referred to as low-grade tumours and 3 and 4 as high-grade.

Like most brain tumours, the cause of a mixed glioma, or any type of glioma, is unknown. Research is being carried out into the possible causes.

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

Raised intracranial pressure can cause headaches, sickness (vomiting) and visual problems. Changes in behaviour and personality can also be signs of a mixed glioma.

Common symptoms include headaches and fits (seizures). Other symptoms may relate to the area of the brain that 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 also affect your memory.

If the parietal lobe of the brain is affected, writing and other such activities may be difficult. Hemiparesis may also be present.

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. This is done through a number of tests and investigations.

Neurological examinations (nerve tests) You will usually have a neurological examination to 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 but 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 the 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 a mixed glioma 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 of the brain. 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 the 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.

Consent

Before you have any treatment, your doctor will give you full information about what the treatment involves and explain the aims of the treatment to you. They will usually ask you to sign a form saying that you give your permission (consent) for the hospital staff to give you the treatment. No medical treatment can be given without your consent.

Benefits and disadvantages of treatment

Treatment can be given for different reasons and the potential benefits will vary depending upon the individual situation. If you have been offered treatment that aims to cure your cancer, deciding whether to have the treatment may not be difficult. However, if a cure is not possible and the treatment is to control the cancer for a period of time, it may be more difficult to decide whether to go ahead.

If you feel that you can't make a decision about the treatment when it is first explained to you, you can always ask for more time to decide.

You are free to choose not to have the treatment and the staff can explain what may happen if you do not have it. You don't have to give a reason for not wanting to have treatment, but it can be helpful to let the staff know your concerns so that they can give you the best advice.

Surgery

Where possible, surgery is the first form of treatment for a mixed glioma. The aim of surgery is to remove as much of the tumour as possible without damaging the surrounding brain tissue.

Depending on the size, position and spread of the tumour, it may not be possible to remove it completely and further treatment may be given as a follow-up to surgery.

Some tumours, particularly those that are high-grade, cannot be treated by surgery and these are referred to as inoperable. If surgery is not possible, your doctor will discuss other forms of treatment with you.

Radiotherapy

Radiotherapy treatment is the use of high-energy rays to destroy cancer cells and is often used after surgery to destroy any remaining malignant cells. It may also be used alone 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 that destroy cancer cells. It may be given alone, or together with surgery and/or radiotherapy, to treat a mixed glioma.

You may find the idea of a tumour affecting your brain extremely frightening. The brain controls the body, and not being in control 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 that 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 hsbr 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. However, if the tumour comes back 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 (2nd edition). Raghavan et al. Wiley, 1999.
• Cancer in the Nervous System (2nd edition). Levin. Oxford University Press, 2002.

For further references, please see the general bibliography.