Definition of Metastatic brain tumor:

A metastatic brain tumor is cancer that started in another part of the body and spread to the brain.

Causes, incidence, and risk factors:

Many tumor or cancer types can spread to the brain, the most common being lung cancer, breast cancer, melanoma, kidney cancer, bladder cancer, certain sarcomas, and testicular and germ cell tumors. Some types of cancers only spread to the brain infrequently, such as colon cancer, or very rarely, such as prostate cancer.

Growing brain tumors may place pressure on nearby parts of the brain. Brain swelling due to these tumors also causes increased pressure within the skull.

Metastatic brain tumors are classified depending on the exact site of the tumor within the brain, type of tissue involved, original location of the tumor, and other factors. Rarely, a tumor can spread to the brain, yet the original site or location of the tumor is unknown. This is called cancer of unknown primary (CUP) origin.

Metastatic brain tumors occur in about one-fourth of all cancers that metastasize (spread through the body). They are much more common than primary brain tumors (tumors that start in the brain) and occur in approximately 10 - 30% of adult cancers.