It is possible for any type of cell within the brain or spinal cord to undergo neoplastic change. The bony confines of the skull means that mere growth and displacement of existing tissue causes disturbance - hence the phrase space occupying lesion; mass effects and focal signs result. Some are invasive and replace normal tissue.
The most common primary brain tumour is the glioma. Primary tumours of the neurones are rare. Secondary metastases are common, spreading through the bloodstream or by direct invasion.
- estimated there are around 10,000 new cases of primary brain tumours per year
- tumours come from the brain tissue or its coverings - the meninges
- malignant high-grade gliomas (anaplastic gliomas and glioblastomas) and pre-malignant low-grade gliomas come from the brain tissue glial cells, and make up over 60% of primary brain tumours
- meningiomas make up a further 30%
- although often thought benign, meningiomas can have an acute presentation and are associated with significant long-term neurological morbidity. Because of this, they can behave in a malignant fashion in terms of recurrence and impact
- over 60% of people with primary brain tumours present at, and are diagnosed by, accident and emergency services rather than from conventional GP or specialist referral
- primary malignant brain tumours represent only 3% of all cancers - concern that the true incidence of these tumours is rising
- cancers that have spread to the brain from somewhere else in the body are called secondary brain tumours, or brain metastases
- many different cancer types can spread to the brain, with lung and breast cancers being the most common
- peak age of presentation of brain cancer is between 65 and 69
Children and adults tend to be affected by different tumours. Medulloblastomas, pilocytic cerebellar astrocytomas, teratomas, pinealomas and craniopharyngiomas are confined to children and adolescents. Gliomas of the hemispheres, meningiomas, neurinomas, pituitary adenomas are seen in adult life into old age.