Brain tumour. Coloured magnetic resonance imaging (MRI) scan of a coronal section through the brain of a 74 year old woman, showing a large tumour. At upper centre is the tumour (blue) within one cerebral hemisphere (orange) of the brain; the other cerebral hemisphere (at centre left) is normal containing a dark ventricle or cavity. The cerebellum of the brain is seen at lower centre. Brain tumours may be primary tumours arising in the brain first or they may be spread from cancer elsewhere in the body. A large tumour such as this may cause brain compression and nerve damage.