Astrocytoma

Definition

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 a subtype of the larger group of brain tumors called gliomas.

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, brainstem, and optic nerves in children.

Brain Tumor

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When an astrocytoma is diagnosed, the most important factors are:

  • Grade of tumor (how aggressive it appears when viewed microscopically)
  • Size
  • Location
  • Degree of neurological side effects produced by the tumor
  • Age of the patient

These factors will determine the symptoms, prognosis, and treatment.

Causes

The exact cause of astrocytoma is unknown. Some possible causes of brain tumors include:

  • Heredity
  • Certain occupations
  • Environmental factors
  • Viruses

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:

  • Genetic disorders (including neurofibromatosis and tuberous sclerosis)
  • Occupational exposure to:
    • Radiation
    • Chemicals
    • Oil refining
    • Rubber manufacturing

Symptoms

The first symptoms of astrocytoma, or any brain tumor, can be caused by increased pressure in the brain as the tumor grows. Symptoms may include:

  • Headaches
  • Visual changes
  • Vomiting
  • Seizures
  • Personality changes
  • Problems with memory, thinking, and concentration
  • Problems with walking

Symptoms will vary, depending on the location of the astrocytoma. For example:

  • Frontal lobe—gradual changes in mood and personality, paralysis on one side of the body
  • Temporal lobe—problems with coordination, speech, and memory
  • Parietal lobe—problems with sensation, writing, or fine motor skills
  • Cerebellum—problems with coordination and balance.
  • 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:

  • MRI scan —a test that uses magnetic waves to define the anatomy of the brain, the most sensitive and clearest way to define a brain tumor
  • CT scan —an x-ray device that takes circular pictures of the brain using x-ray beams
  • Angiogram —x-rays taken after a dye is injected into the arteries, allowing the doctor to look for abnormalities in the arteries that lead to the brain
  • Biopsy/resection —removal of a sample of brain tissue to test for cancer cells

Grading

Once the test results are confirmed, the pathologist will determine the grade of the tumor. Astrocytomas are graded from I to IV. These grades indicate the prognosis and rate of tumor growth.

  • Grades I and II—These low-grade astrocytomas grow slowly and generally stay localized in an area of the brain. They are more commonly found in younger patients. Grade I astrocytomas are typically well circumscribed. Grade II astrocytomas, much like grades III and IV, are infiltrating tumors.
  • Grades III and IV—These high-grade tumors grow rapidly and can spread throughout the brain and spinal cord. Aggressive treatment is necessary. This is the most common type of astrocytoma found in adults. Grade III tumors are called anaplastic astrocytoma, while grade IV tumors are called glioblastoma multiforme or GBM.

Treatment

Treatment is based on the location, size, and grade of the tumor. Treatment may include:

Surgery

Surgery involves the removal of as much of the tumor as safely possible. If the tumor is high grade, surgery will typically be followed by radiation or chemotherapy to help prevent further spread.

Radiation Therapy (or Radiotherapy)

Radiation therapy involves 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 (also called brachytherapy)—radioactive materials placed into the body near the cancer cells

Chemotherapy

Chemotherapy is the use of drugs to kill cancer cells. This treatment may be given in many forms, including pill or intravenously (by IV or port). 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 cell phone may increase the risk of developing brain tumors, but, to date, there is no 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

CANADIAN RESOURCES:

Brain Tumor Foundation of Canada
http://www.btfc.org/braintumour.nsf/eng/home

Canadian Cancer Society
http://www.cancer.ca

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/ . Accessed October 12, 2005.

Cohen KJ, Broniscer A, Glod J. Pediatric glial tumors. Curr Treat Options Oncol. 2001;2:529-536.

New York University Medical Center, Department of Neurosurgery website. Available at: http://www.med.nyu.edu/neuro/ . Accessed October 12, 2005.



Last reviewed November 2007 by Rimas Lukas, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.


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