A brain tumor occurs when cells grow uncontrollably in the brain. Cancer occurs when cells in the body divide without control or order. If cells divide uncontrollably, they form a mass of tissue. The mass is called a growth or tumor. The term cancer usually refers to malignant tumors. These can invade nearby tissue and spread to other parts of the body. A benign tumor does not spread. But, it can continue to grow and press structures near it, causing symptoms.

There are two main types of brain tumors:

  • Primary brain cancer—This begins in the brain. It can be either malignant or benign. A small benign tumor in a bad location can cause significant problems.
  • Secondary or metastatic brain cancer—This has spread to the brain from another site in the body. All metastatic tumors are malignant.

Brain Tumor
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The cause of most primary brain cancers is unknown. Secondary brain cancer is caused by the cancer spreading to the brain from another site.