What is a tumour?
A tumour is an abnormal mass of tissue that develops when there is a mutation in the way that cells divide and grow. When the workings of a cell become abnormal, the cell keeps dividing, causing more and more abnormal cells to develop, and eventually leading to the formation of a tumour.
What is a primary brain tumour?
A tumour that begins to develop in the brain is known as a primary brain tumour. Primary brain tumours can develop in various areas of the brain, including the nerve cells (neurons); glial cells (supporting cells for neurons); and the membranes that surround the brain (meninges).
The two most common types of primary brain tumours are gliomas and meningiomas. Gliomas develop from the glial cells, and include astrocytomas; oligodendrogliomas; and glioblastomas.
Other types of primary brain tumours include pituitary tumours, pineal gland tumours, ependymomas, primary central nervous system lymphomas, schwannomas; and craniopharyngiomas.
What is a metastatic brain tumour?
A metastatic brain tumour is a tumour that is caused by the spread of cancer cells from a different part of the body to the brain. Also known as secondary tumours, metastatic tumours are more common than primary tumours.
Metastatic brain tumours generally grow quickly and can cause considerable damage to the brain tissue. Some of the cancers which more commonly spread to the brain include melanoma, breast cancer; kidney cancer, and lung cancer. In some cases, the tumour can develop years after the primary cancer.
What causes primary brain tumours?
Although there are certain genetic syndromes which increase a person’s risk of brain tumours, in the majority of cases the cause of brain tumours is unknown.
What are the symptoms of a brain tumour?
The brain is made up of different areas, each with a different role in controlling the functions of the body. The symptoms of a brain tumour depend on where the tumour is in the brain, the size of the tumour, and how much swelling the tumour is causing in the brain.
Warning signs of a brain tumour include headaches (especially those which are worse upon waking up, and feel better after vomiting); unexplained changes in vision, speech or hearing; difficulties with balance; new onset seizures; a change in mental function like memory loss or confusion; sensory changes such as in the ability to taste or smell; and muscle weakness in the face or part of the body.
How are brain tumours diagnosed?
The process of diagnosing a brain tumour usually involves taking a detailed history, followed by a neurological examination. A CT scan of the head, usually followed by an MRI, is then done to visualise the brain and look for any abnormalities. In most cases any abnormal growth will then be biopsied by a neurosurgeon for further testing.
How are brain tumours treated?
The treatment for a brain tumour will depend on its type, size, and location.
In some cases, active surveillance (closely following a patient but not giving any upfront treatment) may be used. Active surveillance is used with slow growing tumours to avoid or delay treatment. A patient who is on active surveillance will be seen frequently for physical examinations and scans. Treatment is initiated if the patient’s tumour starts to grow more quickly or if he/she becomes symptomatic.
In some cases, surgery is used to treat brain tumours. The decision for surgery is made with careful consideration to the possible risks as well as the potential benefit. Frequently surgery is followed by chemotherapy or radiation.
Radiation therapy uses high energy x-rays to kill cancer cells. Radiation therapy is often used after surgery to target any cancer cells which were left behind, or alone in cases where surgery would be too dangerous to attempt. Specialised techniques can be used to help keep the radiation from causing damage to the normal tissues of the brain. These techniques include intensity modulated radiation therapy (IMRT) and stereotactic radiosurgery (SRS). See the section on radiotherapy for more information.
Chemotherapy is medication which is used to treat cancer by disrupting the life cycle of cancer cells. Unlike surgery and radiotherapy, chemotherapy works throughout the body and not only in the brain. Chemotherapy is sometimes used in order to avoid or delay surgery and/or radiotherapy. It is also used in high grade brain tumours alongside surgery and radiotherapy. There are various chemotherapy regimens used for brain tumours. Some of these drugs are taken by mouth and some are given into a drip. The type used depends on the type and grade of tumour.
Targeted therapy works by targeting specific genes or proteins which are involved in cancer growth. Because their targets are specific to the cancer cells they do not have the same side effects as chemotherapy. Not all brain tumours can be treated with targeted treatment but research and developments in this field are evolving continuously.