Introduction
Each year in Europe an estimated 25,000 people are diagnosed with brain and central nervous system tumours.
There are many different types of brain tumours. Tumours that develop from cells in the brain are usually referred to as primary brain tumours. A short description of each of these is given in the Brain Tumours section below.
The brain is also a common site for cancers that have spread from other parts of the body including the lung, breast and digestive system. These secondary cancers (metastases) are mentioned only briefly in this section.
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The Brain
The brain operates the nervous system controlling both conscious and subconscious actions. It is made up of 100 billion nerve cells or neurones, each connected to 10,000 other cells, about 1000 trillion in all. The brain also contains glial cells. These provide support, nourishment and protection for neurones. Astrocytes, oligodendrocytes and ependymal cells are all types of glial cells.
The main parts of the brain are:
- The cerebrum. The cerebrum is divided into right and left hemispheres (the right side controls the left side of the body, and the left hemisphere controls the right side). Each hemisphere is divided into lobes - the frontal lobe, temporal lobe, parietal lobe and occipital lobe. Through the nerves connected to the spinal cord, the brain receives information from all our senses. There are special areas for interpreting what we see, hear, taste, smell and feel. Separate regions of the brain have specialised functions, such as controlling the movement of specific body parts and operating the mental processes of speech, memory, personality and our emotional response.
- The cerebellum. It sits beneath the cerebrum. It controls balance and coordination, and can affect speech as well as walking and other movements.
- The brain stem. This controls basic bodily functions such as the heartbeat, breathing, and blood pressure – the things that you do not normally think about, but which are essential to life. Nerves from the cerebrum pass through the brain stem to the spinal cord, and through other nerves to every part of the body.
- The meninges. These are thin layers of tissue called the dura and arachnoid meninges that cover the brain. The cerebrospinal fluid circulates around the brain and spinal cord under the arachnoid.
- The pituitary gland. This releases various hormones into the bloodstream.
The brain is the most complex organ in the human body and many aspects of its function are still not properly understood. We do know, however, that the effect of anything that interferes with brain function will vary according to the part of the brain which is affected, and that usually this will result in symptoms occurring in the part of the body that the affected area controls.
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Brain Tumours
There are many different types of brain tumour. The main types are:
Gliomas
About half of all brain tumours are gliomas. There are four main types of glioma: astrocytoma, ependymoma, oligodendroglioma, and a mixed glioma, which as the name suggests, is a mixture of the other types.
- Astrocytomas are the most common type of glioma and occur in both adults and children. Astrocytomas develop from cells called astrocytes and vary in the speed that they grow and how clear the boundary is between the tumour and the rest of the brain. Astrocytomas are subdivided into:
- Mixed Gliomas are a mixture of the different types of glioma, and so vary in how they grow and whether or not they spread to other areas. In general, these tumours behave very much like astrocytomas.
Acoustic Neuroma
Acoustic neuromas grow in the auditory nerve that connects the ear to the brain and controls hearing and balance. They often cause deafness on the affected side. They are slow growing and do not spread to other parts of the brain or elsewhere in the body. They are most often found in middle-aged and older people, but younger people with neurofibromatosis also develop these tumours.
Craniopharyngioma
Craniopharyngiomas are tumours that tend to affect children, teenagers and young adults. They do not usually spread, but can affect vision and hormone balance, resulting in weight gain and growth problems in children.
Haemangioblastoma
Haemangioblastomas grow from blood vessels. They tend to be slow-growing and do not spread to other parts of the brain.
Lymphoma
Lymphomas can start in the brain, particularly in people who have had an organ transplant or have AIDS, because their immune systems are suppressed. Lymphomas in the brain and spinal cord are not the same as lymphomas found in the rest of the body and tend to be more difficult to treat.
Meningioma
Meningiomas are the second most frequent form of brain tumour, and account for approximately 25% of all brain tumours in adults, usually affecting older people and, more commonly, women. They are tumours that grow from the meninges, the tissues that cover the brain. They are not usually cancerous but depending on their location in the brain can cause significant symptoms, usually due to pressure they apply on surrounding structures.
Pineal Gland Tumours
Pineal gland tumours are rare. They start in the pineal gland, which makes melatonin a hormone believed to have some function in the normal day-night cycle.
Pituitary Tumours
Pituitary gland tumours are usually benign and curable. The pituitary gland produces a number of hormones and so controls a wide range of body functions. Tumours can cause too much or too little of these hormones to be produced as well as having other effects by pressing on nearby structures, most importantly the optic nerves connecting the eyes to the brain. Pituitary tumours include:
Primitive NeuroEctodermal Tumour (PNET)
Medulloblastoma is the commonest form of primitive neuroectodermal tumour. These tumours tend to grow in the cerebellum (responsible for balance and coordination) and are the most common brain tumour in children, but can also affect young adults. Medulloblastomas can grow very quickly and may spread to other parts of the brain and spinal cord through the cerebrospinal fluid.
Secondary Brain Tumours (Metastases)
Other forms of cancer can spread to the brain through the blood stream. Often there will be just one, two or three of these tumours present. If these are detected at an early stage using CT or MRI scans some can be treated using surgery or various forms of radiotherapy.
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Diagnosing Brain Tumours
There are a number of tests that can be performed to diagnose brain tumours.
Various types of brain scan, including a CT (Computerised Tomography) or MRI (Magnetic Resonance Imaging) scan will often confirm the presence of a brain tumour. However, it is only through a biopsy - taking a sample of tissue from the tumour, or sometimes taking fluid from around the spinal cord and examining it under a microscope in a laboratory – that the various forms of tumour can be distinguished and an accurate diagnosis can be made.
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Brain Tumour Risk Factors
The cause of most brain tumours remains unknown.
Exposure to electromagnetic fields from power lines and electronic devices such as mobile and cordless phones has not been proven to be a risk factor.
The only two proven risks are high doses of radiation to the head (for example in people previously treated with radiotherapy) and rare genetic conditions, including neurofibromatosis, who are more likely to develop acoustic neuromas and meningiomas. In the vast majority of cases, there is no identifiable cause for the tumour to have developed.
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Preventing Brain Tumours
There is no proof that the development of brain tumours is related to exposure to electromagnetic fields, although some pressure groups argue that mobile (cell) phones should be used as infrequently as possible, and that people should not live in the immediate vicinity of power lines.
Unfortunately, as there are no risk factors for the majority of these tumours, there are no practical steps that can be taken to minimise the risk of developing brain tumours.
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Symptoms of Brain Tumours
The effect of anything that interferes with brain function will vary according to the part of the brain which is affected. Usually, this will result in symptoms occurring in the part of the body that the affected area controls.
Headaches can be due to a number of causes. Although rare, they can be the result of increased pressure on the brain as the tumour grows within the confines of the skull. Typically this headache is worse in the morning.
Brain tumours can also cause convulsions (fits), visual problems, depression and confusion.
Specific symptoms, which can also indicate which part of the brain is affected include:
- numbness
- sensory changes or weakness in a particular part of the body
- loss of coordination which can also be in a particular part of the body
- personality changes
- speech problems
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Treating Brain Tumours
Brain tumours can be treated using surgery and a number of forms of radiotherapy depending on the type of tumour that has been found. Chemotherapy tends to be less useful in treating brain tumours.
Surgery
Brain surgery is the preferred treatment option for many brain tumours. If removing the tumour is not possible without damaging normal brain tissue, radiotherapy may be the better option, but surgery may still be required in these cases to obtain a sample of the tumour so that an accurate diagnosis can be made, or to relieve symptoms caused by raised pressure within the brain.
Brain surgery usually involves cutting a hole in the skull (a craniotomy). However, operations on the pituitary gland, for example, will involve operating through the nose and the base of the skull.
The aim of surgery is always the same: to remove as much of the tumour as possible without damaging more normal brain tissue than is absolutely necessary. Any tumour that is left behind is usually treated with radiotherapy but in young children chemotherapy may be preferred to avoid long term side effects.
External Beam Radiotherapy
External radiotherapy uses high energy X-ray beams generated from machines to kill cancer cells. Some normal cells will also be affected, but the treatment is planned so that the radiation is focused on the affected areas from a variety of different angles. Normal tissues, therefore, receive a much smaller dose. In addition, normal cells are better at repairing themselves than cancer cells.
Before any treatment can be given there is a careful planning phase. This includes obtaining an exact diagnosis, being sure about the exact location, size and shape of the tumour, so that the best treatment options can be worked out.
External radiotherapy is normally given as a series of short regular treatments in a radiotherapy department (each treatment may be referred to as a fraction). Radiotherapy is usually given using a linear accelerator.
There are a number of new very sophisticated forms of radiotherapy which may be used in the treatment of some localised brain tumours:
- Stereotactic radiotherapy (SRT) is a form of high-precision radiotherapy that is now becoming available in many centres. SRT provides radiotherapy focused on the whole tumour, with very little effect on surrounding normal tissues. This allows the use of very high doses of radiation in 3-8 treatment sessions or fractions over a two week period. During SRT patients are positioned very precisely during treatment to minimise radiation of nearby normal tissues. SRT also includes measures to allow for movement of the tumour during imaging and treatment planning as well as during radiotherapy.
- Radiosurgery is a form of stereotactic radiotherapy, where the treatment is given in one long session, instead of a number of shorter sessions. Multiple beams of radiation focus precisely on the tumour. In this way, very high doses of radiation can be delivered to a small target area where the cancer is, and so destroying it.
- Tomotherapy delivers radiation to tumours with little effect on surrounding normal tissues. The radiation source rotates around the patient and is delivered with extreme precision using thousands of small beams. Using this system the area around the spinal cord but not the spinal cord can be treated. Daily CT scans are used to plan the treatment precisely allowing for the smallest of changes in tumour size.
Chemotherapy
Chemotherapy is the use of drugs to kill cancer cells. Treating brain tumours with drugs can be difficult as many drugs do not cross from the blood vessels into the brain. This is called the blood-brain barrier, which is usually very helpful in keeping harmful substances out of the brain. If drugs that do not cross the blood-brain barrier are required in the treatment of a tumour, they can be given directly into the cerebrospinal fluid.
Chemotherapy may be given to try to prevent a brain tumour from recurring after surgery, or to treat recurrences if they occur, to treat a brain tumour where surgery is not possible or to shrink a tumour so that surgery is easier.
Not all brain tumours respond to chemotherapy - for more details see the treatment for specific brain tumours below.
Chemotherapy is often given instead of radiotherapy in young children. This is to avoid the long term side effects of radiotherapy in children under 3 years of age.
Astrocytomas
Slowly growing astrocytomas with a clear boundary can often be treated successfully by surgery - removing the tumour. This is often referred to as resection, but sometimes the tumour can recur. Even if the entire tumour cannot be removed, it may remain inactive or be successfully treated with radiotherapy.
Anaplastic Astrocytoma
Radiotherapy and chemotherapy combined is the standard treatment in some but not all European countries.
Glioblastoma Multiforme
Radiotherapy and chemotherapy combined is the standard treatment.
Ependymomas
Surgery is the usual form of treatment for an ependymoma.
Radiotherapy is used to treat any remaining parts of the tumour that could not be removed, or on its own, to treat tumours that cannot be removed surgically.
Chemotherapy is used in very young children (under 3 years) as an alternative to radiotherapy.
Oligodendrogliomas
The practical approach to treating these tumours, which do not have a clear boundary, is to remove as much of the tumour as possible without damaging the surrounding brain tissue, with radiotherapy after surgery.
Mixed Gliomas
The usual approach to treating mixed gliomas is to remove as much of the tumour as possible without damaging the surrounding brain tissue, with radiotherapy after surgery.
Acoustic Neuromas
These may be removed surgically. However, this often results in damage to the auditory nerve and deafness on the affected side.
A new alternative is radiosurgery, which is a form of radiotherapy not surgery. This treats small target areas (less than 3-4cm in size) very accurately, causing little or no damage to surrounding structures.
Stereotactic radiotherapy can be provided over several days or in one long session when the treatment may be referred to as radiosurgery.
Craniopharyngiomas
Craniopharyngiomas are very difficult tumours to treat. They are benign tumours but because they develop deep in the brain it is impossible to remove them completely. Surgery combined with radiotherapy is one option for treatment. Another option is radiosurgery, which is a form of radiotherapy. This treats small target areas (less than 3-4cm in size) very accurately, causing little or no damage to surrounding structures.
Haemangioblastomas
Haemangioblastomas do not tend to spread into surrounding areas. It is possible to remove many of them with surgery. Some haemangioblastomas can develop in a part of the brain where surgery is very difficult. In these cases, external beam radiotherapy or its high-precision form, radiosurgery, is often very successful.
Lymphomas
Treatment of CNS lymphoma generally consists of a combination of chemotherapy and corticosteroids. Radiotherapy is used in the treatment of lymphomas which do not respond to chemotherapy.
Meningiomas
Surgery is the first line of treatment for meningiomas. Some meningiomas can develop in a part of the brain where surgery is very difficult, and in these cases external beam radiotherapy is the treatment of choice.
Pineal Gland Tumours
Surgery is very difficult for pineal tumours because the gland lies deep in the brain. If the tumour cannot be completely removed by surgery, radiotherapy and chemotherapy can be given after surgery.
Pituitary Tumours
Treatment depends on the type of pituitary tumour and whether it has spread into the surrounding brain. Surgery, radiotherapy and in some cases drugs (hormones) are all used in treatment.
Medulloblastoma
Surgery is an important part of treatment for a child with a medulloblastoma. Radiotherapy is always used after surgery to kill any tumour cells left behind after surgery of that have spread though the cerebrospinal fluid to other parts of the brain and spinal cord. Chemotherapy has an increasing role in the treatment of these tumours.
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Looking after Yourself
There are many different types of brain tumour and they all need different treatment. The brain is the most complex organ in the human body and any treatment that interferes with brain function can affect the part of the body that the affected area of the brain controls.
Some tumours in certain parts of the brain can affect movement, control of movement, personality, thinking, speech and swallowing. A number of therapists – physiotherapists, speech and language therapists, occupational therapists and psychologists are available to help with these specific problems and more detail on the help they can provide can be found in the Help from Other Professionals section.
Many patients will experience hair loss following chemotherapy or radiotherapy. Usually this is temporary and the hair grows back after the treatment finishes. Wigs are one way of dealing with this problem, although many patients find it easier just to wear a scarf or hat until their hair regrows.
Feeling sleepy and not having any energy are common side effects that last for up to 6 weeks following treatment, so you have to be realistic about how much you can do during this time and avoid driving if you are not fit to drive.
Loss of appetite and feeling sick are also quite common but rarely a major problem.
Whatever the problem is, do not assume that nothing can be done about it – ask your doctor or nurse: do not just grin and bear it.
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Questions for your Doctor
Before making up your mind about the best treatment option for you, you will need information about your cancer, the treatments available in your area and what they will involve, what to expect from the treatment, what side effects you might experience and how these may change over time as well as what your doctors believe would be most effective in combating your cancer.
For different patients the answers will also be different, so it is important to discuss all these issues with your doctor so that you are able to make the right choice for you.
You will have your own questions but some issues you might want to raise are:
- What does the treatment involve?
- What are the benefits I might get?
- How good are my chances of getting those benefits?
- Could having treatment make me feel worse? If so, in what way?
- Are there alternative treatments?
- What are the risks of the treatment?
- Are the risks minor or serious? How likely are they to happen?
- What care will I need after treatment?
- What happens if something goes wrong?
- What may happen if I don’t have the treatment?
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Conclusion
There are many different forms of brain tumours, with different forms of treatment. For clinical and personal reasons particular treatments will suit some patients better than others. Patients, therefore, need comprehensive information so that they are able to make the right decision for them.
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