| Brain tumors occur when cells in the brain begin to | | | | locked into place by the skull and can't move out |
| divide out of control and start to displace or | | | | of the way if a tumor is growing near it. Even a |
| invade nearby tissues. Occasionally, brain tumors | | | | benign tumor can cause pressure on the brain, |
| can spread throughout the body. One of the | | | | and this pressure can be both symptomatic and |
| special characteristics of brain tumors is that | | | | life-threatening. Metastases are tumors which |
| benign (non-cancerous) tumors in the brain can be | | | | have spread from a cancer that started in a |
| just as bad as malignant (cancerous) brain tumors. | | | | different body part; they do not start in the brain, |
| Any of the various normal cell types of the brain | | | | but instead take up residence there after traveling |
| can mutate and become a primary tumor, and | | | | from a separate cancer (like a lung cancer or |
| the particular cell type which makes up the tumor | | | | breast cancer). |
| controls how the tumor is likely to behave. It is | | | | |