Abnormal growths developing in brain tissue or the coverings of the brain
- Most common between the ages of 60 and 70. Some types occur only in children
- More common in males
- Genetics and lifestyle are not significant factors
Brain tumours may be cancerous or noncancerous. Unlike most tumours in other parts of the body, cancerous and noncancerous brain tumours can be equally serious. The seriousness of a tumour depends on its location, size, and rate of growth. Both types of tumour can compress nearby tissue, causing pressure to build up inside the skull.
Tumours that first develop in brain tissues are called primary tumours. They can arise from various types of brain cell, including the brain’s support cells (tumours of which are called gliomas) and cells in the meninges (meningiomas). Gliomas are often cancerous, but most meningiomas are noncancerous. Primary brain tumours are slightly more common in men and usually develop between the ages of 60 and 70. Some types only affect children (see Brain and spinal cord tumours in children). Pituitary tumours are those that arise in the pituitary gland, at the base of the brain.
Secondary brain tumours (metastases) are more common than primary tumours. They are always cancerous, having developed from cells that have been carried in the blood from cancerous tumours in areas such as the breast or the lungs. Several metastases may develop in the brain simultaneously.
What are the symptoms?
Symptoms usually occur when a primary tumour or metastasis compresses part of the brain or raises the pressure inside the skull. They may include:
Headache that is usually more severe in the morning and is worsened by coughing or bending over.
Nausea and vomiting.
Other symptoms tend to be related to whichever area of the brain is affected by the tumour and may include:
Difficulty in reading and writing.
Change of personality.
Numbness and weakness of the limbs on one side of the body.
A tumour may also cause seizures (see Epilepsy). Sometimes, a tumour blocks the flow of the cerebrospinal fluid, which circulates in and around the brain and spinal cord. As a result, the pressure inside the ventricles (the fluid-filled spaces inside the brain) increases and causes further compression of brain tissue. Left untreated, drowsiness can develop, which may eventually progress to a state of coma and death.
How are they diagnosed?
If your doctor suspects a brain tumour, he or she will refer you to hospital for immediate assessment by a neurologist. You will have CT scanning or MRI of the brain to look for a tumour and check its location and size. If these tests suggest that a tumour has spread from a cancer elsewhere in the body, you may need to have other tests, such as chest X-rays or mammography, to check for tumours in the lungs or breasts. You may also need to have a brain biopsy, in which a sample of the tumour is removed surgically under general anaesthesia. The sample is then examined in a laboratory to find the type of cell from which the tumour has arisen.
What is the treatment?
Treatment for brain tumours depends on whether there is one tumour or several, the precise location of the tumour, and the type of cell affected. Primary brain tumours may be treated surgically. The aim of surgery is to remove the entire tumour, or as much of it as possible, with minimal damage to the surrounding brain tissue. Surgery will probably not be an option for tumours located deep within the brain tissue. Radiotherapy may be used in addition to surgical treatment, or as an alternative to it, for both cancerous and noncancerous primary tumours. Chemotherapy may also be an option for certain types of primary tumours. Small meningiomas may not be treated if they are not causing problems; in such cases, regular monitoring is carried out to ensure that, if any problems do develop, they are detected and treated early.
As brain metastases are often multiple, surgery is not usually an option. However, in cases where there is a single metastasis, surgical removal may be successful. Multiple tumours are usually treated with radiotherapy or, less commonly, with chemotherapy.
Other treatments may be necessary to treat the effects of brain tumours. For example, the drug dexamethasone (see Corticosteroids) may be given to reduce the pressure inside the skull, and anticonvulsant drugs may also be prescribed to prevent or treat seizures. If a tumour blocks the flow of cerebrospinal fluid in the brain and fluid builds up in the ventricles, a small tube may be inserted through the skull to bypass the blockage.
What is the prognosis?
The outlook for primary brain tumours varies considerably, depending on their location, size, rate of growth, type of cell they affect, and whether they can be surgically removed or respond well to other treatments. The outlook is usually better for a noncancerous tumour that grows slowly; for example, overall about 8 in 10 people with a slow-growing, noncancerous meningioma survive for at least 5 years after diagnosis. In contrast, for the most aggressive type of glioma, the average life expectancy of adults after diagnosis is 11 months, and overall fewer than 6 in 100 adults survive for more than 5 years. In general, the outlook for children tends to be better than for adults.
For people with secondary brain tumours (metastases), the overall outlook is poor. Most people do not live longer than 6 months, although in rare cases a person with a single metastatic tumour may be cured.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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