A metastatic brain tumor is cancer that has spread (metastasized) from another part of the body to the brain. It is also called a secondary tumor, lesion or brain metastasis (plural: metastases). In contrast, a primary brain tumor starts in the brain, not in another part of the body.
A tumor is an abnormal mass of tissue. It occurs when cells divide more than they should or don't die when they should.
Cancers that spread to the brain can originate in any part of the body. The original tumor is called the primary tumor. Metastatic brain tumors most commonly originate in the lung, breast, skin, colon, and kidney. A very aggressive form of skin cancer called melanoma often spreads to the brain.
Brain metastases occur when cancer cells break away from a primary tumor. They travel to the brain, usually through the bloodstream. These cancer cells may settle in the brain and continue growing. Sometimes only one secondary brain tumor occurs. But in many cases there are multiple lesions.
The brain is a complex organ enclosed in the skull. Among other things, it serves as the body's center of