Astrocytoma is a malignant, or cancerous, type of brain tumor. This type of tumor arises from small, star-shaped cells in the brain called astrocytes. Astrocytes are one of several types of supporting cells in the brain called glial cells. Therefore, an astrocytoma is sometimes called a glioma.
Astrocytoma is the most common form of glioma, and may occur anywhere in the brain. However, it is most commonly found in the cerebrum in adults, and in the cerebellum in children.
When an astrocytoma is diagnosed, the most important factors are:
These factors will determine the symptoms, prognosis, and treatment.
Causes
The exact cause of astrocytoma is unknown. Some possible causes of brain tumors include:
Risk Factors
A risk factor is something that increases your chances of getting a disease or condition. Although the exact risk factors for astrocytomas have not been identified, some studies implicate the following:
Symptoms
The first symptoms of astrocytoma, or any brain tumor, are caused by increased pressure in the brain as the tumor grows. Symptoms may include:
Subsequent symptoms will vary, depending on the location of the astrocytoma. For example:
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Frontal lobe – gradual changes in mood and personality; paralysis on one side of the body.
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Temporal lobe – problems with coordination, speech, and memory.
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Parietal lobe – problems with sensation, writing, or fine motor skills.
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Cerebellum – problems with coordination and balance.
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Occipital lobe – problems with vision, visual hallucinations
Diagnosis
The doctor will ask about your symptoms and medical history, and perform a physical exam. Tests may include:
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MRI Scan – a test that uses magnetic waves to define the anatomy of the brain; this is the most sensitive and clearest way to define a brain tumor
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CT Scan – a common x-ray device that takes circular pictures of the brain using x-ray beams
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Angiogram – x-rays taken after a dye is injected into the arteries; allows the doctor to look for abnormalities in the arteries that lead to the brain
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Biopsy – removal of a sample of brain tissue to test for cancer cells
Grading
Once the test results are confirmed, your doctor will determine the grade of the tumor. Tumors are graded from I to IV. These grades indicate the prognosis and rate of tumor growth.
Grades I and II – low-grade astrocytomas. These grow slowly and generally stay localized in an area of the brain. They are the primary type found in children.
Grades III and IV – high-grade tumors. They grow rapidly and can spread throughout the brain and spinal cord. Aggressive treatment will be necessary. This is the most common type of astrocytoma found in adults. Grade III tumors are called anaplastic astrocytoma. Grade IV tumors are called glioblastoma multiforme.
Treatment
Treatment is based on the location, size, and grade of the tumor. Treatment may include:
Surgery – surgical removal of the tumor and possibly nearby tissues. If the tumor is high grade, surgery should be followed by radiation or chemotherapy to help prevent further spread.
Radiation Therapy (or Radiotherapy) – the use of radiation to kill cancer cells or shrink the tumor. Radiation may be:
External Radiation Therapy – radiation directed at the tumor from a source outside the body
Internal Radiation Therapy – radioactive materials placed into the body near the cancer cells
Glucocorticoid Medication – cortisone drugs, such as dexamethasone, given to decrease swelling in the brain.
Chemotherapy – the use of drugs to kill cancer cells. Chemotherapy may be given in many forms including: pill, injection, or by catheter. The drugs enter the bloodstream and travel through the body killing mostly cancer cells, but also some healthy cells.
Prevention
There are no guidelines for preventing astrocytoma because the exact cause is not known. It has been suggested that the electromagnetic waves emitted from high-tension wires or even cellular phone may increase the risk of developing brain tumors, but, to date, there is not scientific evidence supporting this theory.
RESOURCES:
American Brain Tumor Association
http://www.abta.org
American Cancer Society
http://www.cancer.org
CancerNet, National Institutes of Health
http://www.cancer.gov/cancer_information
References:
Adjuvant systemic chemotherapy, following surgery and external beam radiotherapy, for adults with newly diagnosed malignant glioma. National Guideline Clearinghouse website. Available at: http://www.guideline.gov/summary/summary.aspx?view_id=1&doc_id=5351. Accessed October 12, 2005.
New York University Medical Center, Department of Neurosurgery website. Available at: http://www.med.nyu.edu/neuro/. Accessed October 12, 2005.
