Brain Cancer

The brain is enclosed within the hard casing of the skull. With one exception, cancer that begins in the brain does not metastasise to other parts of the body, yet the brain is a common site for a metastasis from elsewhere.

Symptoms

The most common first symptom of a brain tumour is persistent headache; this is caused by the increasing pressure of the growing cancer on normal brain tissue. Headaches may be associated by increasing irritability or unusual sleepiness. The more rapidly the tumour grows the more disturbing the symptoms it causes. These include nausea, vomiting, loss of hearing, taste, balance, sight, speech or control of movement. Sudden epileptiform seizures and temporary loss of consciousness occur in about one-third of brain cancer cases.

Diagnosis

The diagnosis of a brain tumour starts with the examination of the optic nerve which connects the retina of the eye with the brain. An ophthalmoscope is used to look at the retina. A tumour compressing the nerve results in swelling of the nerve-ending in the retina; this is called papilloedema. The clinical examination is completed by examination of muscle function, reflexes and ability to feel pinpricks.

The greatest recent advance in brain tumour diagnosis is the CAT scan, which allows detailed examination of the brain in thin crosssectional slices. The brain’s electrical activity can be recorded by a method called electro-encephalography (or EEG). Electrodes are attached to the scalp and electrical readings are recorded by the machine. (Both the CAT scan and the EEG are totally painless and the patient feels nothing at all.) If the picture of the CAT scan is not clear some tissue may be removed for examination to confirm the diagnosis.

Sometimes the arteries supplying blood to the brain are outlined by a dye and an X-ray is taken; this is called angiography. The purpose is to detect a change in the usual pattern of these arteries caused by their displacement as the tumour grows. This examination is carried out under anaesthetic and is not painful.

Treatment

Brain tumours can be treated by surgery, radiotherapy, anti-cancer drugs and a combination of these methods. Surgery is the oldest method and a neurosurgeon can sometimes remove a cancer that is encapsulated in a membrane and so cure the condition. If the whole of the tumour cannot be removed, part of it will be cut away to relieve the pressure that the growing tumour is causing within the skull and with it the unpleasant persistent headache. Radiotherapy is used mainly to shrink the tumour and reduce pressure inside the skull.

Chemotherapy is hampered by the blood-brain barrier that prevents anti-cancer drugs (with the exception of a new group called nitrosoureas which are especially effective in reaching the brain) from getting through the walls of the brain arteries. Only temporary relief has so far been achieved by chemotherapy.