Cerebral metastases are tumours, which originate from outside the Central Nervous System {CNS} (Brain and spinal cord) and spread to it via the blood stream or directly invade from neighbouring tissues. Metastatic tumours are the commonest tumours that affect the Brain and spinal cord. The incidence is around 11 per 100.000 people per year. The incidence increases from 1 in 100,000 below 25 yrs of age to > 30 per 100,000 at age 60. About 30% of adults and 6-10% of Children with Cancer will develop metastasis at some point.
The commonest sites of Cancer in Adults from which spread occurs to the brain are:
The most common sites of cancer in Adults from which spread occurs to the spinal canal or spinal cord are:
80 % of brain metastases are located in cerebral hemispheres. 15% are found in the cerebellum. Diagnosis is established by Contrast CT and contrast MRI scans. It is important to establish not only the site and size of the abnormality in the brain, but also how many abnormal areas are present. Metastases from renal cancer, breast cancer, choriocarcinoma and melanoma are the ones most likely to have areas of bleeding within the tumour. As a general rule around 50% of patients with Brain metastasis have a single abnormality and 30% will have three or more tumours.
The clinical symptoms are essentially the same as for Gliomas and depend on which area of the brain they are located in.