Overview

Brain stem glioma begins when normal cells in the brain stem begin to change and grow uncontrollably, forming a mass called a tumor. A tumor can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body). A glioma is a tumor that grows from a glial cell, which is a supportive cell in the brain.

The brain stem connects the brain to the spinal cord. It is the lowest portion of the brain, located above the back of the neck. The brain stem controls many of the body’s basic functions, such as motor skills, sensory activity, coordination and walking, the beating of the heart, and breathing. It has three parts:

• The midbrain, which develops from the middle of the brain
  
  
• The medulla oblongata, which connects to the spinal cord
  
  
• The pons, which is located between the medulla oblongata and the midbrain

Brain stem glioma is most often diffused (spread freely) through the brain stem by the time of diagnosis. This type of tumor is typically very aggressive, meaning that it grows and spreads quickly. A small percentage of brain stem tumors are very localized or focal tumors. A focal tumor is often a low-grade (the tumor cells look similar to normal cells) tumor that is less aggressive.

Brain stem glioma occurs most commonly in children between five and 10 years old. Most brain stem tumors develop in the pons and grow in a part of the brain stem where it can be difficult to perform surgery, making brain stem glioma challenging to treat.

Statistics

Approximately 3,400 central nervous system (CNS; brain and spinal cord) tumors are diagnosed each year in children under the age of 20. About 850 of these are considered benign tumors. Central nervous system tumors are the second most common childhood cancer after leukemia and brain tumors.

Cancer statistics should be interpreted with caution. Estimates are based on data from thousands of cases of this type of cancer, but the actual risk for a particular individual may differ. It is not possible to tell a person how long he or she will live with a brain stem glioma.

Statistics adapted from the American Cancer Society's publication, Cancer Facts and Figures 2009 and the Central Brain Tumor Registry of the United States.

Find out more about basic cancer terms used in this section.