A brain tumor is a disease in which cells grow uncontrollably in the brain. Eventually these cells form a mass of tissue called a tumor. If the tumor invades nearby tissue or spreads to other parts of the body, then it is a malignant tumor. A malignant tumor is also known as cancer. Brain cancer can fall into two categories:

  • Primary brain cancer—begins in the brain
  • Secondary or metastatic brain cancer—cancer started somewhere else in the body and spread to the brain. These are also known as metastatic tumors.

If the tumor does not invade other tissue it is considered a benign tumor. Although a benign tumor does not spread, it can cause damage by pressing on nearby brain tissue.

Brain Tumor
Copyright © Nucleus Medical Media, Inc.

The cause of most primary brain cancer and benign tumors is unknown. Researchers believe that the tumors may be due to defects in genes. These defects trigger cells to grow uncontrollably.

Secondary brain cancer is caused by the cancer spreading to the brain from another site.