Education: Neurological Cancer
Types of Brain Tumors
There are several types of brain tumors. Brain tumors are categorized by the type of cell where the tumor begins, or the area of the brain where they occur. The most common types of brain tumors are:
Gliomas—The most common type of primary brain tumor is a glioma. Gliomas begin from glial cells, which are the supportive tissue of the brain. There are several types of gliomas, categorized by where they are found and the type of cells that originated the tumor.
Metastatic Tumors—In adults, metastatic brain tumors are the most common type of brain tumors. These are tumors that begin to grow in another part of the body and then spread to the brain through the bloodstream.
Meningiomas—Meningiomas are usually benign tumors that come from the tough outer covering of the brain just under the skull. They are slow growing and may exist for years before being detected. Meningiomas are usually separate from the brain and can sometimes be removed entirely during surgery.
Schwannomas—Schwannomas are benign tumors, similar to meningiomas. They arise from the supporting cells of the nerves leaving the brain and are most common on the nerves that control hearing and balance.
Pituitary Tumors—The pituitary gland is a gland located at the base of the brain. It produces hormones that control many other glands in the body. Tumors that occur in or around the area of the pituitary gland can affect the functioning of the gland or overproduce hormones that are sent to the other glands. Tumors in the pituitary are frequently benign, and total removal makes the tumors less likely to recur.
Primitive Neuroectodermal Tumors (PNET)—PNET can occur anywhere in the brain, although the most common place is in the back of the brain near the cerebellum. When they occur here, they are called medulloblastomas. These tumors are fast growing and often malignant, with occasional spreading throughout the brain or spinal cord.
Craniopharyngioma—Benign tumors that occur at the base of the brain near the nerves from the eyes to the brain and the hormone centers are called craniopharyngiomas. Most persons with this type of brain tumor develop symptoms before the age of 20. Although these tumors are benign, they are hard to remove due to the sensitive brain structures that surround them.
Pineal Region Tumors—Many different tumors can arise near the pineal gland, a gland that helps control sleep and wake cycles. Gliomas are common in this region, as are pineal blastomas, a type of tumor that wraps itself around the pineal gland in the brain. A blastoma is a malignant tumor whose cells have undeveloped (embryonic) characteristics.
In addition, germ cell tumors, another form of malignant tumor, can be found in this area. Tumors in this region are more common in children than adults. Biopsy or removal of the tumor is frequently necessary to tell the different types of tumors apart.
Most brain tumors show evidence of genetic abnormalities that can result in uncontrolled cell growth. Patients with certain genetic conditions such as neurofibromatosis, Von Hippel-Lindau disease (a genetic condition involving the abnormal growth of blood vessels in some parts of the body which are particularly rich in blood vessels), Li-Fraumeni syndrome (a rare hereditary cancer predisposition syndrome), and retinoblastoma (a cancer of the eye that develops in children) are at increased risk for developing tumors of the central nervous system. Occasionally, people in the same family who do not have any of these genetic conditions may develop brain tumors.
Research additionally suggests that exposure to certain chemicals may increase a person’s risk for developing neurological cancer. Workers in oil refining and rubber manufacturing and chemists have a higher incidence of certain types of malignant tumors. Despite this increased incidence however, scientists have not been able to link any particular chemical toxin to this increase.
Patients who have received radiation therapy to the head as part of prior cancer treatment also are at increased risk for neurological cancer.