A central nervous system (CNS) tumor begins when normal cells in the brain or the spinal cord begin to change and grow uncontrollably, forming a mass. A tumor can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body). The brain is the center of thought, memory, and emotion. It controls the five senses (smell, touch, taste, hearing, and sight), movement, and other basic functions of the body, including heartbeat, circulation, and breathing. The spinal cord consists of nerves that carry information back and forth between the body and the brain.
A tumor located in the CNS is especially problematic because a person’s thought processes and movements can be affected. This type of tumor also may be challenging to treat because the tissues surrounding the tumor may be vital to the body’s functioning.
Anatomy of the brain
The brain is composed of four major parts: the cerebrum, cerebellum, brain stem, and meninges.
The cerebrum, the largest part of the brain, contains two cerebral hemispheres and is divided into four lobes where specific functions occur.
- The frontal lobe controls reasoning, emotions, problem solving, and parts of speech and movement
- The parietal lobe controls the sensations of touch, pressure, pain, and temperature
- The temporal lobe controls memory and the sense of hearing
- The occipital lobe controls vision
The cerebellum, or "little brain," is located beneath the cerebrum. The cerebellum controls coordination and balance.
The brain stem, which is the lowest portion of the brain and connects to the spinal cord, controls involuntary functions essential for life, such as heartbeat and breathing.
The meninges are the membranes that surround and protect the brain and spinal cord. There are three meningeal layers, called the dura mater, arachnoid, and pia arachnoid.
Types of CNS tumors
There are many different types of CNS tumors. Some are cancerous and very likely to grow and spread (called very aggressive or high grade), others are less aggressive (low grade), and others are noncancerous, which means they are not likely to grow and spread. The following types of CNS tumors are most common among children:
Statistics
Approximately 3,400 CNS tumors are diagnosed each year in children under the age of 20. About 850 of these are considered benign (non-cancerous) tumors. CNS tumors are the second most common childhood cancer, after leukemia. The overall five-year relative survival rate (the percentage of people who survive at least five years after the cancer is detected, excluding those who die from other diseases) for CNS tumors is 74%.
Cancer survival statistics should be interpreted with caution. These 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 CNS tumor. Because the survival statistics are measured in five-year intervals, they may not represent advances made in the treatment or diagnosis of this cancer.
Statistics adapted from the American Cancer Society's publication, Cancer Facts and Figures 2009.
Find out more about basic cancer terms used in this section.
Last Updated: July 24, 2009
