Epidemiology of brain metastases.

Brain metastases are one of the most common neurologic complications of cancer. The incidence is 9%-17% based on various studies, although the exact incidence is thought to be higher. The incidence is increasing with the availability of improved imaging techniques which aid early diagnosis, and effective systemic treatment regimens which prolong life, thus allowing cancer to disseminate to the brain. Lung cancer, breast cancer, and melanoma are the most frequent to develop brain metastases, and account for 67%-80% of all cancers. Most patients with brain metastases have synchronous extracerebral metastases. Some patients present with no known primary cancer diagnosis. In children, brain metastases are rare; germ cell tumors, sarcomas, and neuroblastoma are the common offenders.