Astrocytoma Health Article

Definition

Astrocytoma is a tumor that arises from astrocytes, star-shaped cells that play a supportive role in the brain.

Description

The brain acts as a computer that controls all of the functions of the body. It stores information, memories, and with the use of hormones and electrical impulses, regulates and sends instructions to the rest of the body. Because of the brain's importance, cancers in the brain can affect many of the body's functions. The location of a tumor within the brain determines which effects it will have. Astrocytomas may occur in the cerebrum, the site of thought and language, the cerebellum, the area responsible for movement and muscle co-ordination, or the brainstem, the location that regulates critical activities like breathing and heartbeat. Childhood astrocytomas are most commonly located in the cerebellum, while adults usually develop astrocytoma in the cerebrum.

Astrocytomas rarely metastasize (spread) outside the brain to other parts of the body; however, they may grow and spread within the brain. As there is no extra room in the skull, the presence of a brain tumor causes an increase in intracranial (within the skull) pressure, resulting in headaches and possibly affecting normal brain function by compressing delicate brain tissue.

Astrocytomas are a type of glioma, a tumor of glial cells (specialized cells that give physical support and electrical insulation between neurons). They are sometimes called gliomas, anaplastic astrocytomas, or glioblastoma multiforme. Oligoastrocytomas are a type of mixed glioma similar to astrocytomas. They usually contain cells that originate from oligodendrocytes as well as astrocytes, and are usually low grade (grading is an estimate of the tumor's malignancy and aggressiveness; lower-grade tumors require less drastic therapy than high-grade tumors).

Demographics

Astrocytoma occurs slightly more often in males than in females. It is also slightly more common in Caucasians than in those of African or Asian descent. Although it affects both adults and children, children usually develop a less serious form with a better prognosis. The total incidence of all types of brain cancer, including astrocytomas, is approximately 13 people out of every 100, 000.

Causes and symptoms

The cause of astrocytoma is not known. Brain cancer may occasionally be caused by previous radiation treatments; however, x rays are not believed to play a role. As of 2001, studies have indicated that the moderate use of handheld cellular phones does not cause brain cancer; ongoing research will determine if long-term cellular phone use causes an increase in cancer incidence.

Some studies suggest that brain tumors may occur more frequently in people who have occupational exposure to certain chemicals, including some pesticides, formaldehyde, vinyl chloride, phenols, acrylonitrile, N-nitroso compounds, polycyclic aromatic hydrocarbons, lubricating oils, and organic solvents. The greatest risk is associated with exposure before birth or during infancy.

There is a slightly higher incidence of astrocytoma in the siblings and parents of people with this tumor; however, only one type of astrocytoma is known to have a genetic cause. The rare subependymal giant cell astrocytoma occurs in conjunction with tuberous sclerosis, a hereditary disorder.

A wide variety of symptoms develop as a result of astrocytoma, including the following:

• headache
• nausea and vomiting
• neck stiffness or pain
• dizziness
• seizures
• unsteadiness in walking or unusual gait
• lack of coordination, decreased muscle control
• visual problems such as blurring, double vision, or loss of peripheral vision
• weakness in arms or legs
• speech impairment
• altered behavior
• loss of appetite

Because there are several different types of astrocytoma, not all patients will show the same symptoms. The location of the tumor within the brain will determine which symptoms a patient will experience. Because the tumor causes an increase in intracranial pressure, most people with astrocytoma will develop headaches and nausea and vomiting.