What Is a Brain Tumor?

Brain anatomy illustrating tumor and tumor cells

A brain tumor is an abnormal growth of tissue in the brain. The tumor can either originate in the brain itself (primary brain tumor), or come from another part of the body and travel to the brain (metastatic or secondary tumor). Brain tumors are classified as either benign (non-cancerous) or malignant (cancerous), depending on their location, size and behavior.

A benign brain tumor does not contain cancer cells and once it is removed it usually does not recur. Most benign brain tumors have clear borders, meaning they do not invade the surrounding tissue. These tumors can however cause symptoms similar to cancerous tumors depending on size and location.

Malignant brain tumors do contain cancer cells. They are usually fast growing and invade surrounding tissue. Malignant brain tumors very rarely spread to other areas of the body, but may recur within the brain even after treatment. Sometimes brain tumors that are not cancerous are called malignant because of their size and location and the damage they can therefore do to vital functions of the brain.

Metastatic brain tumors are tumors that begin to grow in another part of the body and then spread to the brain through the lymph nodes and bloodstream. Common types of cancer that can travel to the brain include lung cancer, breast cancer, nasopharyngeal cancer, melanoma (a type of skin cancer), and colon cancer. Metastatic cancers are described and treated based on the specific type of the original cancer. For example, breast cancer that has spread to the brain is called metastatic breast cancer.

How common is brain cancer?

Brain cancer is a brain tumor that has been diagnosed as being malignant.

The American Cancer Society's estimates for malignant brain and spinal cord tumors in the United States for 2011 are cited here. They include both adults and children. These statistics are only for brain cancer cases that begin as tumors in the brain. If the statistics included tumors that migrated to the brain (metastatic tumors), the numbers would be much higher.

About 22,340 malignant tumors of the brain or spinal cord (12,260 in males and 10,080 in females) were diagnosed in 2011. Overall, the chance that a person will develop a malignant brain tumor or spinal cord tumor in his or her lifetime is less than 1% (about 1 in 150 for a man and 1 in 185 for a woman).

Survival rates for malignant brain tumors vary widely. The rates depend on the type of tumor and many other factors, including where the patient is treated and how experienced the physicians are who are responsible for treating the patient with neurosurgery, radiation or chemotherapy. To receive the best brain cancer diagnosis and treatment possible, it is important to be seen at the Stanford Brain Tumor Center.

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Open trials refer to studies currently accepting participants. Closed trials are not currently enrolling, but may open in the future.

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