A brain tumor is a collection of cells that grow out of control. As they continue to grow, they form a mass of cells that becomes a tumor. Brain tumors form in 1 of 2 ways:
- primary brain tumor starts with an abnormal brain cell and grows in the brain.
- metastatic (secondary) tumor starts as a cancer in another part of the body (such as the lungs or breast) and then spreads to the brain, where it forms a new tumor.
Doctors don’t know why some cells begin to form into tumor cells. It may have something to do with a person’s genes or his or her environment, or both.
The tumors can cause local damage by growing and pushing on crucial areas of the brain. They can also cause problems if they block the flow of fluid around the brain, which can lead to an increase in the pressure inside the skull. Some types of tumors can spread through the spinal fluid to distant areas of the brain or the spine.
A primary brain tumor can be malignant or benign:
- A malignant tumor is more dangerous because it can grow quickly and may grow into or spread to other parts of the brain or to the spinal cord. Malignant tumors are also sometimes called brain cancer. Metastatic brain tumors are always malignant because they have spread to the brain from other areas of cancer in the body.
- A benign primary brain tumor is not cancer. Benign tumors can cause damage by growing and pressing on other parts of the brain, but they don’t spread. In some cases, a benign tumor can turn into a malignant tumor.
Symptoms of a brain tumor depend on the size and location of the tumor, as well as other factors. They may include:
- Weakness or numbness
- Changes in speech, vision, hearing, or personality
- Feeling drowsy
- Problems with balance or walking