Brain tumours

A brain tumour is a mass of cells growing where there is no spare room. The skull does not stretch, so even a small, slow-growing mass can seriously disturb how the brain works: what matters is less the size than what it presses on. Tumours are divided into primary ones, which arise from brain tissue itself or its coverings, and secondary ones, made of cells carried by the blood from a tumour elsewhere in the body. Secondary tumours are considerably more common than primary ones.

Why "benign" does not mean "harmless"

Brain tumours are described by a grade from one to four, which reflects how fast the cells grow and how readily they come back after removal. Grades one and two mean slow growth; grades three and four, aggressive growth.

Inside a closed skull, though, the word "benign" describes the behaviour of the cells, not the consequences for the person. A slow tumour of the coverings that grows beside the brainstem or the optic nerve is dangerous precisely because of where it sits: reaching it is difficult, and it presses on structures nobody can do without. Conversely, a mass in a "silent" area of the frontal lobe may give no sign for years, until it becomes large.

Grade alone is no longer enough: the type of tumour is refined by the molecular features of the cells. Both the choice of treatment and the outlook depend on them.

How a tumour announces itself

The signs come from two sources: rising pressure inside the skull, and loss of function in whatever area is being squeezed.

• A headache unlike the usual one: worse in the morning, waking you at night, building up when you cough, bend forward or strain, and becoming more frequent over time.
• Nausea and vomiting unrelated to meals, most often in the first half of the day.
• A first-ever seizure in an adult, one of the commonest opening signs.
• Slowly increasing weakness or numbness in the arm and leg on one side.
• Speech becomes hard work: words will not come, or they sound slurred.
• Part of the visual field drops out, vision doubles, or objects on one side stop being noticed.
• Changes in character: apathy, uncharacteristic sharpness, gaps in memory. Family often notice this before the person does.
• Constant drowsiness and slowness.

None of these on its own points to a tumour: headaches, weakness and seizures far more often have other causes. What matters is not the symptom but its behaviour — it is new, it lasts for weeks and it keeps getting worse.

When waiting for a routine appointment is not an option

• a seizure has happened for the first time;
• the face suddenly droops, an arm gives way or speech disappears — a stroke starts the same way and minutes count;
• the person is increasingly hard to rouse and is confused about what is going on;
• a severe headache comes together with vomiting and double vision;
• the worst headache of a lifetime, reaching full force within seconds.

In these situations you call emergency services rather than book an appointment.

Where secondary tumours come from

Metastases in the brain are more common than tumours that start in the brain itself. They come above all from lung cancer, breast cancer, melanoma, kidney cancer and bowel cancer. Sometimes the lesion in the head is found first and the original tumour is looked for afterwards, which is why a finding on the scan is followed by examination of the lungs, the skin and the breasts.

Hence a practical point. If someone has ever been treated for cancer, however long ago, and now develops headaches, seizures or weakness in one arm, they should say so at the very first consultation. That single fact changes the whole order of investigation.

What affects the risk and what does not

The cause of most brain tumours remains unknown. Among the established factors are age, exposure of the head to ionising radiation (above all radiotherapy received in childhood) and a few rare inherited syndromes: neurofibromatosis types 1 and 2, tuberous sclerosis and Li-Fraumeni syndrome. Long-term suppression of the immune system raises the likelihood of lymphoma of the central nervous system.

What has shown no link: mobile phones, phone masts and household appliances, power lines, an old blow to the head, stress, or the type of diet. A CT scan of the head carries a tiny radiation dose, and where there is a genuine indication the benefit is incomparably greater — which is exactly why children are not scanned "just in case".

What is inherited is not the tumour but a rare syndrome that raises the risk. The vast majority of cases are not familial, and relatives of a patient need no testing without a specific reason.

How the diagnosis is made

The main method is MRI of the brain with contrast. CT is quicker and therefore comes first in an emergency: it shows bleeding and gross swelling well. Examining the back of the eye reveals swelling of the optic disc, an indirect sign of raised pressure inside the skull.

One caveat deserves emphasis, because patients often do not know it: a scan shows a mass but not its nature. An abscess, a patch of multiple sclerosis, a lymphoma, a metastasis and the scar of a stroke can all look alike. Only examination of the tissue itself gives a diagnosis — a biopsy, or material removed at operation. Molecular tests are added to it, and waiting several weeks for the result is normal rather than a delay.

What treatment involves

The plan depends on the type of tumour, where it sits, its size, and the person's age and general condition. Several approaches are usually combined.

• Watching. A small, slow mass found by chance is sometimes simply followed with repeat scans.
• Surgery. The aim is to remove as much tumour as can be removed safely. Near the speech areas the operation is sometimes done with the person awake, so that speech can be checked as the surgery proceeds.
• Radiotherapy. Used after surgery, or instead of it where access is impossible; for single metastases a small, precisely targeted volume is irradiated.
• Drug treatment. Chemotherapy and targeted medicines are chosen according to tumour type and the molecular findings.

Supportive treatment runs alongside. Corticosteroids reduce the swelling around a tumour and can clear some symptoms within days, but they are given in short courses and not continued without need. Anticonvulsants are for people who have already had a seizure, not for everyone. Recovery of speech, movement and memory is the work of a speech therapist, a rehabilitation doctor and a physiotherapist, and it is worth starting early.

The outlook varies enormously: some tumours are removed completely and the person recovers, others require years of treatment. The average survival figures easily found online lump together dozens of different diseases and say little about any individual. One practical detail: after a seizure or brain surgery there are restrictions on driving, and it is worth asking your doctor about the timing in advance.

Online consultation

In an online consultation the doctor will go through how the headaches and other complaints have changed, judge whether any features call for urgent investigation, explain which test makes sense first and what the scan reports you already have actually mean. If the situation is urgent, you will be told so plainly and pointed towards face-to-face care.

This material is for information only and does not replace medical advice.