Epidemiology

• ▶ Each year about 16 000 people are diagnosed in the UK with a brain tumour (which is rare compared with many other cancers—for example, breast, lung, colorectal), but primary malignant brain tumours have a high case fatality.

• ▶ They are the commonest cause of cancer related deaths in young men (under 45 years) and women (under 35 years), and are the commonest solid tumour in children.

• ▶ There is a bimodal pattern of incidence, highest in the very young and in the elderly, with men exceeding women across the age spectrum (except meningiomas).

• ▶ Annual incidence appears to be increasing, particularly for gliomas and primary CNS lymphomas, likely due to better case ascertainment with greater availability and access to imaging.

• ▶ Most brain tumours are sporadic, the cause unknown and therefore they are not preventable.

• ▶ Rare causes include previous exposure to ionising radiation, neurocutaneous syndromes (eg, neurofibromatosis, tuberous sclerosis, von Hippel–Lindau syndrome) and genetic tumour syndromes (eg, Li Fraumeni syndrome).

• ▶ The role of mobile phones is unclear and recent data do not suggest an increased risk of glioma and meningioma.

• ▶ About 20% of patients with cancer outside the nervous system develop brain metastases which are also becoming more common due to increasing survival from systemic disease.

WHO classification

The WHO classification (table …