What is a primary brain tumour?

Tumours start in cells in our body. Cells are tiny building blocks that make up the organs and tissues of our bodies. They divide to make new cells in a controlled way. This is how our bodies grow, heal and repair.

A tumour develops when the normal workings of a cell go wrong and the cell becomes abnormal. The abnormal cell keeps dividing, making more and more abnormal cells. These eventually form a lump (tumour).

Cells forming a tumour
Cells forming a tumour

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Primary brain tumours

Our information on primary brain tumours is relevant for people with benign and malignant brain tumours. A tumour that starts in the brain is called a primary brain tumour. They can be either benign (not cancer) or malignant (cancerous) and there are many different types.

Benign brain tumours usually grow slowly and may not cause symptoms for a long time. They are very unlikely to spread but they can cause problems as they grow and press on nearby areas of the brain. Some benign brain tumours do not come back after treatment but others may, and will need further treatment. Sometimes a benign brain tumour can change over time and become malignant.

Malignant brain tumours grow faster than benign tumours. They cause problems by spreading into and damaging nearby areas of the brain. Some tumours may spread to other parts of the brain or the spinal cord. They very rarely spread to other parts of the body. Malignant brain tumours are more likely to come back after treatment.

Doctors who specialise in treating brain tumours may describe a brain tumour as being benign or malignant. But often they find it more useful to describe brain tumours by the type of tumour and how slowly or quickly it grows (its grade).

We have separate information about tumours that have started somewhere else in the body and spread to the brain. These are called secondary brain tumours or brain metastases.

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Secondary brain tumours

Secondary brain tumours happen when cancer cells spread to the brain from a cancer in another part of the body.