The central nervous system, or CNS, is composed of the brain and the spinal cord. According to the National Cancer Institute, brain cancer, also known as an intracranial neoplasm, is the growth of abnormal cells in the tissues of the brain. Primary brain tumors start in the brain, while secondary brain tumors arise from somewhere else in the body and then metastasize, or spread, to the brain. These types of tumors are also called metastatic brain cancer.
Brain tumors may be benign (non-cancerous) or malignant (cancerous). Both benign and malignant tumors may cause symptoms as they may put pressure on nearby structures within the brain. However, benign tumors will not invade other tissues, while cancerous, or malignant, tumors will actively spread and invade nearby tissues in the brain and even elsewhere in the body. The prognosis, or chance of recovery, depends on a multitude of factors, which include the type of brain cancer, its location, its size, speed of growth, and the baseline health of the individual patient.
Brain tumors are classified by the type of brain cell from which the cancer developed. Brain cancer types include the following:
- Adenoma or craniopharygioma – which arises from brain cells in the pituitary gland
- Sarcoma – which arises from connective tissues within the brain
- Pinealoma – which arises from the pineal gland in the brain
- Osteoma and osteosarcoma – both of these arise from the bones of the skull
- Meningioma – arise from the outside layers of the brain, or the coverings
- Medulloblastoma – arise from the cerebellum
- Hemangioblastoma – arise from the cells that develop the arteries and veins within the brain
- Gliomas – arise from the glial cells, which serve as support cells for neurons, or the information carrying cells of the brain. Gliomas are the most common brain tumors and account for 65% of cases. A specific type of glioma is the glioblastoma multiforme, or GBM, which is the type of brain cancer most often found in adults. Other types of gliomas are astrocytomas, oligodendrogliomas, and ependymomas.
It is estimated that nearly 70,000 new cases of primary malignant and non-malignant brain and CNS (central nervous system) tumors will be diagnosed in the United States in 2015. More than 3,000 new cases of childhood primary malignant and non-malignant brain and CNS tumors will be diagnosed in 2015. Nearly 14,000 deaths will be attributed to primary malignant brain and CNS tumors in the US in 2015.