A brain tumor is an abnormal mass of tissue in which cells grow and multiply uncontrollably. Primary brain tumors originate in the brain and rarely spread to other parts of the body.
Metastatic (or secondary) brain tumors come from cancer cells in another part of the body and develop as a tumor in the brain. The site where the cancerous cells originated is referred to as the primary cancer.
The diseased cells spread to the brain by moving through the bloodstream and continue growing in their new location. This spread of a tumor to a new part of the body is called metastasis, and the primary cancer is said to have metastasized.
There has been an increase in metastatic brain tumors, as people are surviving primary cancers for longer periods of time.
