An adult brain tumor is a disease in which abnormal cells form in the tissues of the brain.
There are many types of brain and spinal cord tumors. The tumors are formed by the abnormal growth of cells and may begin in different parts of the brain or spinal cord. Together, the brain and spinal cord make up the central nervous system (CNS).
The tumors may be either benign (not cancer) or malignant (cancer):
- Benign brain and spinal cord tumors grow and press on nearby areas of the brain. They rarely spread into other tissues and may recur (come back).
- Malignant brain and spinal cord tumors are likely to grow quickly and spread into other brain tissue.
When a tumor grows into or presses on an area of the brain, it may stop that part of the brain from working the way it should. Both benign and malignant brain tumors cause signs and symptoms and need treatment.
Brain and spinal cord tumors can occur in both adults and children. However, treatment for children may be different than treatment for adults. (See the PDQ summary on Childhood Brain and Spinal Cord Tumors Treatment Overview for more information on the treatment of children.)
For information about lymphoma that begins in the brain, see the PDQ summary on Primary CNS Lymphoma Treatment.
A brain tumor that starts in another part of the body and spreads to the brain is called a metastatic tumor.
Tumors that start in the brain are called primary brain tumors. Primary brain tumors may spread to other parts of the brain or to the spine. They rarely spread to other parts of the body.
Often, tumors found in the brain have started somewhere else in the body and spread to one or more parts of the brain. These are called metastatic brain tumors (or brain metastases). Metastatic brain tumors are more common than primary brain tumors.
About half of metastatic brain tumors are from lung cancer. Other types of cancer that commonly spread to the brain are melanoma and cancer of the breast, colon, kidney, nasopharynx, and unknown primary site. Leukemia, lymphoma, breast cancer, and gastrointestinal cancer may spread to the leptomeninges (the two innermost membranes covering the brain and spinal cord). This is called leptomeningeal carcinomatosis.