[Epidemiology of brain metastases]

The incidence of intracerebral metastasis is largely underestimated. They appear to be the most frequent cause of intracerebral tumors with an average incidence of probably more than 12/100 000 inhabitants per year. Depending on reports, 25 to 35% of cancer patients will develop brain metastasis. In neurosurgical series, the frequency of cerebral metastasis among surgical procedures for brain tumors increased from 3.5 to 12%. We reviewed the literature in order to better know the frequency of intracerebral metastasis depending on the type of primary cancer. The rate of other metastatic lesions, the duration between discovery of the primitive cancer and brain metastasis were found to be useful for selection of patients for neurosurgical treatment. Three types of cancers could be defined, regarding the incidence of brain metastasis. While occurrence of brain metastases is very high, surgery should often be useless; if brain metastases only occur in the late stage of a cancer, then, surgery should be discussed according to the general status of the patient; although brain metastasis is rare in a cancer, surgery will often be required for diagnosis and treatment.