Most malignant brain tumours are caused by a cancer that started somewhere else in the body and spread to the brain through the bloodstream.
The cause of primary malignant brain tumours (cancerous tumours that start in the brain) is not fully understood.
Underlying disease
Some genetic conditions can increase your risk of a primary malignant brain tumour. These conditions include:
These conditions tend to cause malignant gliomas (see Malignant brain tumour - introduction) that appear in childhood or early adulthood, whereas most gliomas start later in adulthood.
Other possible causes
Radiotherapy to the brain increases your risk of brain tumour, although this is still uncommon.
It is also thought that family history of brain tumours and exposure to chemicals (such as formaldehyde) may be risk factors.
