Brain metastasis

A brain metastasis is a cancer that has metastasized (spread) to the brain from another location in the body and is therefore considered a secondary brain tumor.^[1][2] The metastasis typically shares a cancer cell type with the original site of the cancer.^[3] Metastasis is the most common cause of brain cancer, as primary tumors that originate in the brain are less common.^[4] The most common sites of primary cancer which metastasize to the brain are lung, breast, colon, kidney, and skin cancer. Brain metastases can occur months or even years after the original or primary cancer is treated. Brain metastases have a poor prognosis for cure, but modern treatments allow patients to live months and sometimes years after the diagnosis.^[5]