General Information About Adult Brain Tumors
|Anatomy of the brain, showing the cerebrum, cerebellum, brain stem, and other parts of the brain.||Anatomy of the inside of the brain, showing the pineal and pituitary glands, optic nerve, ventricles (with cerebrospinal fluid shown in blue), and other parts of the brain.|
The spinal cord connects the brain to nerves in most parts of the body.
The spinal cord is a column of nerve tissue that runs from the brain stem down the center of the back. It is covered by three thin layers of tissue called membranes. These membranes are surrounded by the vertebrae (back bones). Spinal cord nerves carry messages between the brain and the rest of the body, such as a signal from the brain to cause muscles to move or from the skin to the brain about the sense of touch.
There are different types of brain and spinal cord tumors.
Brain and spinal cord tumors are named based on the type of cell they formed in and where the tumor first formed in the CNS. The grade of a tumor may be used to tell the difference between slow- and fast-growing types of the tumor. The grade of a tumor is based on how abnormal the cancer cells look under a microscope and how quickly the tumor is likely to grow and spread.
Tumor Grading System
- Grade I (low-grade) - The tumor grows slowly, has cells that look a lot like normal cells, and rarely spreads into nearby tissues. It may be possible to remove the entire tumor by surgery.
- Grade II - The tumor grows slowly, but may spread into nearby tissue and may recur (come back). Some tumors may become a higher-grade tumor.
- Grade III - The tumor grows quickly, is likely to spread into nearby tissue, and the tumor cells look very different from normal cells.
- Grade IV (high-grade) - The tumor grows and spreads very quickly and the cells do not look like normal cells. There may be areas of dead cells in the tumor. Grade IV brain tumors are harder to cure than lower-grade tumors.
An astrocytic tumor begins in star-shaped brain cells called astrocytes, which help keep nerve cells healthy. An astrocyte is a type of glial cell and is sometimes called a glioma. Astrocytic tumors include the following:
- Brain stem glioma: A brain stem glioma forms in the brain stem, which is the part of the brain connected to the spinal cord. It is often a high-grade tumor, which spreads widely through the brain stem and is hard to cure. A brain stem glioma rarely occurs in adults. (See the PDQ summary on Childhood Brain Stem Glioma Treatment for more information.)
- Pineal astrocytic tumor: A pineal astrocytic tumor forms in tissue around the pineal gland and may be any grade. The pineal gland is a tiny organ in the brain that makes melatonin, a hormone that helps control the sleeping and waking cycle.
- Pilocytic astrocytoma (grade I): A pilocyticastrocytoma grows slowly in the brain or spinal cord. It may be in the form of a cyst and rarely spreads into nearby tissues. This type of tumor is most common in children and young adults and in people with neurofibromatosis type 1 (NF1). A pilocytic astrocytoma rarely causes death.
- Diffuse astrocytoma (grade II): A diffuse astrocytoma grows slowly, but often spreads into nearby tissues. Sometimes a diffuse astrocytoma progresses to a higher grade and becomes an anaplastic astrocytoma or a glioblastoma. A diffuse astrocytoma can form in any part of the brain but most often forms in the cerebrum. It is most common in young adults and in people with Li-Fraumeni syndrome. It is also called a low-grade diffuse astrocytoma.
- Anaplastic astrocytoma (grade III): An anaplastic astrocytoma grows quickly and spreads into nearby tissues. An anaplastic astrocytoma may progress to a higher grade and become a glioblastoma. An anaplastic astrocytoma forms most often in the cerebrum and is most common in adults. An anaplastic astrocytoma is also called a malignant astrocytoma or high-grade astrocytoma.
- Glioblastoma (grade IV): A glioblastoma grows and spreads very quickly. A glioblastoma forms most often in the cerebrum. This type of tumor is most common in adults. This type of tumor has a poor prognosis. It is also called glioblastoma multiforme.