A brain tumor is a growth of abnormal cells in the tissues of the brain. A brain tumor can be benign (non-cancerous) or malignant (cancerous).
There are two basic groups of malignant growths — a brain tumor that starts in the brain tissue itself (primary brain tumor) and a tumor that spreads from someplace else in the body (metastatic brain tumor).
Metastatic brain tumors are described by their tissue of origin (lung, breast, kidney, etc.). Malignant primary brain tumors are described by their cell type and histologic appearance, both of which will determine the rate of growth of the tumor.
There are more than
120 types of brain tumors. A noncancerous (or benign) brain tumor can be just as difficult to treat as a cancerous brain tumor.
Scientists do not know what causes most primary brain tumors. Viruses, defective genes and certain chemicals are all being explored and researched as possible culprits, but until the causes have been identified, there is no known way to prevent developing a brain tumor.
For a discussion on the risk factors for brain and spinal cord tumors in adults, please see the
American Cancer Society website.
Learn more about: 
Brain Tumor Symptoms and DiagnosisBrain Tumor Treatment