Overview

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Cancer can occur in the brain in one of two ways: as a primary tumor (one that originates in that area) or as a metastasis (a secondary tumor that spreads from a cancer elsewhere in the body). According to the American Cancer Society, about 21,810 people in the United States are diagnosed each year with brain tumors.

Types of Brain Tumors

"Tumor" is a general term for a swelling or new growth of tissue. Malignant tumors (sometimes called anaplastic tumors) contain most cells that are very different from normal cells; most benign tumors are made up of cells that are similar to normal cells. Brain tumors may be malignant or benign; however, because the brain is enclosed in the skull, even benign tumors can be dangerous. The skull cannot expand to make room for a growing tumor, so the tumor may press on or damage delicate brain tissue. Therefore, even a benign brain tumor may behave in a malignant fashion and become life-threatening. Some benign brain tumors can also eventually give rise to malignant cells. For these reasons, instead of "malignant" or "benign," brain tumors are usually described as being "high grade" (rapidly growing) or "low grade" (slowly growing).

The World Health Organization recognizes 126 different types of central nervous system tumors. Most are defined according to the type of cells from which they arise. The most common of these tumors in adults are:

Meningiomas are the most common low-grade brain tumors in adults. They form from the membranes that line the skull and cover the brain, and are often curable with surgery. Glioblastomas, the most common high-grade brain tumors in adults, are probably the most resistant of all cancers to treatment. This is because this tumor type has "fingers" that spread very quickly and penetrate the folds of the brain, making glioblastomas very difficult to remove with surgery and radiation therapy. Oligodendrogliomas may sometimes be confused with malignant astrocytomas because their cellular makeup looks similar under the microscope, but patients with these tumors generally have a better prognosis and are more responsive to therapy.

Spinal Tumors

Different types of cancer may form in the bones, tissues, fluid, or nerves of the spine. Less than 10 percent of spine tumors originate in the spine. Most spine tumors have spread, or metastasized, to the spine from cancers that began in other locations, such as the lung, breast, colon, prostate, kidney, or thyroid gland. Sarcomas, which are cancers of the bone, muscle, or connective tissue, can also spread to the spine.

Most primary and metastatic spine tumors are epidural tumors. These tumors begin in the bones of the spine and compress the spinal dura, which are the membranes that surround the spinal fluid, spinal cord, and nerve roots. Spinal tumors can also occur inside the spinal cord itself (intradural, intramedullary tumors) or inside the dura but outside the spinal cord (intradural, extramedullary tumors).

For more information about these tumors, visit the Spine Tumor information overview on our Web site.