A central nervous system (CNS) tumor begins when normal cells in the brain or the spinal cord 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).
A CNS tumor 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.
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.
Anatomy of the brain
The brain is made up 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 underneath 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 a person's 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:
This section covers CNS tumors diagnosed in children. Learn more about brain tumors in adults .
Find out more about basic cancer terms used in this section .
Looking for More of an Overview?
If you would like additional introductory information, explore these related items on Cancer.Net:
- ASCO Answers Fact Sheet : Read a one-page fact sheet (available in PDF) that offers an easy-to-print introduction for CNS tumors.
- Cancer.Net Patient Education Videos: View short videos led by ASCO experts in childhood cancers  and brain tumors  that provide basic information and areas of research.
- Cancer.Net En Español : Read about CNS tumors in Spanish. Infórmase sobre tumor del sistema nervioso central en español.
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