Mixed gliomas are a specific type of brain tumour that affects the nerve cells in the brain. This information describes mixed gliomas, their symptoms and treatments. It should ideally be read with our general information about brain tumours.
We hope this information answers your questions. If you have any further questions, you can ask your doctor or nurse at the hospital where you are having treatment.
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. 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. Benign tumours may continue to grow, but 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.
Within the brain there are nerve cells, and 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 they develop from: astrocytes, ependymal cells and oligodendrocytes.
A mixed glioma is a 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, which is the main part of the brain.
Each year about 4,700 people in the UK are diagnosed with tumours of the CNS. Many of these tumours are malignant. Mixed gliomas are most common in adults, but they can also occur in children. For unknown reasons, they are more common in men than women.
Grading of mixed gliomas
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Grading refers to the appearance of the tumour under a microscope. The grade gives an idea of how quickly the tumour may grow. There are four grades - grades 1 and 2 are low-grade, and grades 3 and 4 are high-grade.
Causes of mixed gliomas
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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.
Signs and symptoms of mixed gliomas
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The first symptoms of a mixed glioma are likely to be caused by increased pressure within 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 problems with vision. 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 in the frontal lobe of the brain may cause gradual changes in mood and personality. There may also be paralysis (inability to move) on one side of the body. This is called 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.
Tests and investigations for mixed gliomas
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Your doctors need to find out as much as possible about the type, position and size of the tumour so they can plan your treatment. You may have a number of tests and investigations.
The doctor will examine you thoroughly and test your reflexes, and the power and feeling in your arms and legs.
Your doctor will look into the back of your eyes using an ophthalmoscope to see if the nerve at the back of the eye is swollen.
This can be caused by oedema (swelling of the tissues within the brain), which may occur due to an increase in the amount of fluid in the brain.
You will have a CT or MRI scan to find the exact position and size of the tumour.
CT (computerised tomography) scan
A CT scan takes a series of x-rays that build up a three-dimensional picture of the inside of the body. The scan is painless but takes 10–30 minutes. CT scans use small amounts of radiation, which will be very unlikely to harm you or anyone you come into contact with.
You will be given an injection of a dye, which allows particular areas to be seen more clearly. For a few minutes this may make you feel hot all over. If you are allergic to iodine or have asthma you could have a more serious reaction to the injection, so it is important to let your doctor know beforehand.
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. Before the scan you may be asked to complete and sign a checklist. This is to make sure it’s safe for you to have an MRI scan.
Before having the scan, you’ll be asked to remove any metal belongings including jewellery. Some people are given an injection of dye into a vein in the arm. This is called a contrast medium and can help the images from the scan to show up more clearly. During the test you will be asked to lie very still on a couch inside a long cylinder (tube) for about 30 minutes. It’s painless but can be slightly uncomfortable, and some people feel a bit claustrophobic during the scan. It’s also noisy but you’ll be given earplugs or headphones.
To give an exact diagnosis, a sample of cells from the tumour (biopsy) is sometimes taken and examined 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.
Treatment of mixed gliomas
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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)
doctor who specialises in treating illnesses of the brain (neurologist)
doctor who specialises in treating cancer (an oncologist)
specialist nurse and possibly other healthcare 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’s 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 be inserted to drain off the excess fluid.
Before you have any treatment, your doctor will explain its aims and what it involves. 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 for each person. If you have been offered treatment that aims to cure your tumour, deciding whether to have the treatment may not be difficult. However; if a cure is not possible and the treatment is to control the tumour 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’s first explained to you, you can always ask for more time to decide.
You are free to choose not to have the treatment. The staff can explain what may happen if you do not have it. Although you don’t have to give a reason for not wanting to have treatment, it can be helpful to let the staff know your concerns so that they can give you the best advice.
Where possible, surgery is the preferred form of treatment for mixed gliomas. 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 treatment uses 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. These are small, radioactive metal objects that are inserted into the tumour during an operation.
Chemotherapy is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells. It may be given alone to treat mixed gliomas or with surgery and/or radiotherapy.
Medicines for seizures
If you experience seizures you may be given a medicine called an anticonvulsant to help prevent them.
You may find the idea of a tumour affecting your brain extremely frightening. You may experience many emotions including anxiety, anger 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 cancer support specialists. Family members and close friends can also offer support.
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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 that you remain well.
After treatment, you will not be able to drive for at least 1–2 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 types of vehicle, such as an LGV (large goods vehicle) or a PCV (passenger carrying vehicle).
It is your responsibility to contact the DVLA and your doctor will advise you how to do this.
Drivers and Vehicle Licensing Association (DVLA)
The DVLA advises GPs and other members of the medical profession on the medical standards of fitness to drive. Patients should seek advice from their doctors.
This information has been compiled using information from a number of reliable sources, including:
Levin. Cancer in the Nervous System. 2nd edition. 2002. Oxford University Press.
National Institute for Health and Clinical Excellence (NICE).Improving Outcomes for People with Brain and Other CNS Tumours – The Manual. 2006.
Raghavan, et al. The Textbook of Uncommon Cancers. 3rd edition. 2006. Wiley.
Souhami, et al. Oxford Textbook of Oncology. 2nd edition. 2002. Oxford University Press.
Tonn, et al. Neuro-oncology of CNS tumours. 2006. Springer.
Thanks to Dr Catherine McBain, Consultant Clinical Oncologist, and the people affected by cancer who reviewed this edition. Reviewing information is just one of the ways you could help when you join our Cancer Voices network.