Brain cancer describes a disease characterized by the abnormal, rapid and uncontrollable growth of cells in the brain. Brain cancer can originate in several different types of cells, creating different forms of cancer. Any of these forms of cancer can become terminal when the cancer cannot be surgically removed and fails to respond to treatments such as chemotherapy and radiation.
Primary Brain Cancer
Doctors classify a tumor that originates in the cells within and surrounding the brain as primary brain cancer. The majority of primary brain cancers begin in the glial cells, non-nerve cells that make up the supportive tissues of the brain. This type of primary tumor accounts for approximately 65 percent of all primary brain tumors, according to the Merck Manual.
Secondary Brain Cancer
Cancer that originates in other parts of the body can metastasize to the brain resulting in secondary brain cancer. This occurs when cells break off the main tumor and travel through the blood to the brain, as described by Cancer Research UK. Many types of cancers, including breast cancer, lung cancer and a type of skin cancer known as malignant melanoma can spread to the brain. Cancers of the digestive tract and cancer of the blood, known as leukemia, can also spread to the brain resulting in secondary brain cancer. Cancer that originates in the cells of the immune system, known as lymphomas, can lead to secondary brain cancer.
Forms of Glial Cell Tumors
Doctors determine the type of brain cancer based on the type of cell that grows abnormally and the location of that cell within the brain. Although most brain cancer begins in glial cells, doctors name these cancers based on the specific type of glial cell. Astrocytoma tumors begin in the small, star-shaped cells of the brain known as astrocytes, according to the National Cancer Institute. Astrocytomas graded as IV, meaning rapidly growing and highly likely to invade other areas of the brain, are usually classified as glioblastoma multiforme. Glioblastoma multiforme tumors, which account for approximately 23 percent of all primary brain tumors, often contain more than one cell type, making them difficult to treat as described by IRSA.org. Ependymomas describes a tumor that begins in the glial cells in the ventricles of the brain. Cancer that begins in the specialized glial cells that produce myelin, the fatty substance that covers nerves, is known as oligodendroglioma.
Other Forms
Medulloblastoma brain cancer originates in primitive nerve cells in the brain. Although this type of cell usually fails to remain in the body after birth, some children develop medulloblastoma in the cerebellum. Pinealblastoma describes a rapidly growing tumor that begins in the pineal gland, a small gland in the center of the brain. Because of the location, doctors often cannot treat this type of tumor.
Statistics
Because the hard, rigid skull surrounds the brain restricting the ability to expand and the brain controls critical bodily functions, brain cancer is often life-threatening. Primary malignant brain cancer accounts for approximately two percent of all cancers diagnosed in the United States, according to IRSA.org, and leads to approximately 13,000 deaths per year.
