NORD gratefully acknowledges Kenneth D. Aldape, MD, Professor of Pathology, University of Texas MD Anderson Cancer Center, for assistance in the preparation of this report.
An astrocytoma is a tumor that arises from the star-shaped cells (astrocytes) that form the supportive tissue of the brain. Other supportive cells of the brain include oligodendrocytes and ependymal cells. Collectively, these cells are known as glial cells and the tissue they form is known as glial tissue. Tumors that arise from the glial tissue, including astrocytomas, are collectively referred to as gliomas.
The World Health Organization (WHO) classifies astrocytomas into four grades depending on how fast they are growing and the likelihood that they will spread (infiltrate) to nearby brain tissue. Non-infiltrating astrocytomas usually grow more slowly than the infiltrating forms. Infiltrating, or diffuse astrocytomas are more common than non-infiltrating astrocytomas. They are generally more common in men and are most common in the cerebral hemispheres of adult patients. In children they occur both in the cerebral hemispheres as well as the brain stem. Tumors from oligodendrocytes (oligodendrogliomas) are also in the category of infiltrating gliomas and can occasionally be difficult to distinguish from astrocytomas. Some infiltrating gliomas are categorized as mixed oligodendroglioma-astrocytoma (oligoastrocytoma).
Grade I astrocytoma is usually a non-infiltrating tumor. The most common type of grade I astrocytoma is pilocytic astrocytoma which is also known as juvenile pilocytic astrocytoma or JPA. This tumor grows slowly but can become very large. Pilocytic astrocytoma occurs most often in the cerebellum, cerebrum, optic nerve pathway and brainstem. This tumor occurs most often in children and teens and accounts for 2% of all brain tumors.
Grade II astrocytoma is also called low-grade astrocytoma or diffuse astrocytoma and is usually an infiltrating tumor. This tumor grows relatively slowly and usually does not have well-defined borders. It occurs most often in adults between the ages of 20 and 40.
Grade III astrocytoma is also called anaplastic (malignant) astrocytoma because this tumor grows more quickly than a grade II astrocytoma. Anaplastic astrocytoma occurs most often in adults between the ages of 30 and 50, and accounts for 4% of all brain tumors.
Grade IV astrocytoma is also called glioblastoma or GBM and is the most aggressive type of nervous system tumor. It is also referred to as glioblastoma multiforme because of its wide variety of appearances under the microscope. Rarely, non-glial tissue elements can exist in a glioblastoma. The most common variant of GBM showing these additional tissue elements is called a mixed glioblastoma-sarcoma, or gliosarcoma. GBM occurs most often in adults between the ages of 50 and 80, is more common in men, and accounts for 23% of all primary brain tumors.
Recently several markers have been identified in diffuse gliomas. Astrocytomas grades II and III often have acquired mutations in a gene called IDH1. These mutations ar acquired by the tumor and are not generally present in the normal cells of the patient. The presence of an IDH1 mutation in an astrocytoma is generally associated with an improved prognosis compared to an astrocytoma of similar grade that does not have an IDH1 mutation. A second marker, relevant to GBM, is MGMT methylation. When present, MGMT methylation may be associated with better response to chemotherapy (usually temozolomide) compared to GBMs without MGMT methylation.
Symptoms of grade I and grade II astrocytomas are subtle because the brain is able to temporarily adapt to the presence of a slow-growing tumor. Symptoms of grade III and grade IV astrocytomas may be sudden and debilitating. Symptoms can result from increased pressure within the brain and may include headaches, vision changes and nausea or vomiting. Symptoms may also occur based on the location of the tumor due to interference with normal brain function and include focal seizures, difficulty with speaking, loss of balance and weakness, paralysis or loss of sensation of one side of the body. Fatigue and depression are common in individuals with an astrocytoma.
Desmoplastic infantile astrocytoma (DIA) is a very rare grade I astrocytoma. This tumor tends to occur the cerebral hemispheres and is usually diagnosed in children less than two years of age. Symptoms may include an increased head size, bulging soft spots (fontanelles) in the skull, eyes that focus downward and seizures. A related tumor, desmoplastic infantile ganglioglioma, is a mixed astrocytic and neuronal tumor, but is otherwise similar to DIA.
Subependymal giant cell astrocytoma occurs in the ventricles of the brain and is almost always associated with a genetic condition called tuberous sclerosis. Other rare neuroepithelial tumors include pleomorphic xanthoastrocytoma (PXA) and ganglioglioma (a mixed glial-neuronal tumor).
The cause of most astrocytomas is not known. Researchers speculate that genetic and immunologic abnormalities, environmental factors (e.g., exposure to ultraviolet rays, certain chemicals, ionizing radiation), diet, stress, and/or other factors may play contributing roles in causing specific types of cancer. Investigators are conducting ongoing basic research to learn more about the many factors that may result in cancer.
Astrocytomas occur with greater frequency with certain genetic disorders including Turcot syndrome, neurofibromatosis type-I tuberous sclerosis, Ollier’s disease and Li-Fraumeni syndrome.
Grade I astrocytoma occurs most often in children and teens and account for 2% of all brain tumors. Grade II astrocytoma occurs most often in adults between the ages of 20 and 60. Grade III astrocytoma occurs most often in adults between the ages of 30 and 60, is more common in men and accounts for 4% of all brain tumors. Grade IV astrocytoma occurs most often in adults between the ages of 50 and 80, is more common in men and accounts for 23% of all primary brain tumors.
The diagnosis of astrocytoma is based on a thorough clinical evaluation, characteristic physical findings, a careful patient history, and specialized tests, such as blood tests, neuroimaging techniques, and/or other diagnostic studies. Neuroimaging techniques, such as computed tomography (CT) scanning and magnetic resonance imaging (MRI) of the brain assist in evaluating tumor size, location, and other factors. During CT scanning, a computer and x-rays are used to create cross-sectional images of certain tissue structures. MRI uses a magnetic field to create cross-sectional images of particular organs and bodily tissues. Examination of a sample of the tumor (biopsy) and microscopic examination of tumor cells is used to determine the tumor type and grade.
Grade I astrocytoma: Surgery is the standard treatment. Total surgical removal of accessible astrocytomas is often possible and successful. Accessible tumors are those that can be operated on without causing unacceptably severe damage to other parts of the brain. If surgery is performed, the surgeon will attempt to remove all identifiable parts of the astrocytoma when possible. When the astrocytoma involves a crucial part of the brain, partial removal of the growth usually reduces pressure, relieves symptoms and helps control seizures.
Full or partial removal of the astrocytoma is sometimes followed by radiation therapy to destroy any remaining tumor cells. With the use of CT (computed tomography) and MRI (magnetic resonance imaging), radiation sometimes may be deferred for several months or years while the patient is scanned at regular intervals. Radiation as primary therapy is occasionally used on grade I astrocytomas.
Chemotherapy may be administered after radiation in an attempt to destroy any cells that remain or may also be given during the course of radiation treatment. Chemotherapy may be used instead of radiation in very young children to avoid damage to the developing brain. The type of chemotherapeutic drug therapy selected is determined by a neuro-oncologist who examines the grade of tumor, previous treatment and current health status of the affected individual.
Grade I astrocytoma can sometimes progress to a higher grade so follow-up scans at regular intervals are necessary to check for re-growth.
Grade II astrocytoma: Treatment depends on the size and location of the tumor. Surgery may be used to remove accessible tumors. As with all infiltrating astrocytomas (grades II-IV) it cannot be completely removed with surgery because the tentacle-like projections of the tumor grow into the surrounding tissue. Radiation may be used if the tumor is not accessible or in addition to surgery. Grade II astrocytoma can also progress to a higher grade so follow-up is necessary to check for re-growth. A recurrent tumor may be treated with surgery, radiation or chemotherapy.
Grade III astrocytoma: Treatment depends on the size and location of the tumor, what it looks like under the microscope and how far it has spread. The standard treatment is surgery and radiation therapy, accompanied or followed by chemotherapy. If surgery is not possible, radiation and chemotherapy may be recommended. Several different types of radiation therapy are available including conventional external beam radiation, focused radiation, stereotactic radiosurgery implanted radiation or conformal radiation. A radiation oncologist determines the most appropriate form of radiation for a particular tumor. Chemotherapeutic agents that are commonly used to treat grade III astrocytoma include carmustine (BCNU), lomustine (CCNU), procarbazine, cisplatin and temozolomide. Biodegradable wafers (called Gliadel Wafers) containing BCNU is sometimes inserted in the cavity that remains after a tumor is removed. Grade III astrocytoma tend to recur and treatment depends on the grade of tumor that recurs.
The Food and Drug Administration (FDA) has approved temozolomide (Temodar) for the treatment of adults with anaplastic astrocytoma that has not responded to other forms of therapy (refractory anaplastic astrocytoma). For more information, contact:
Merck Corporate Headquarters
2000 Galloping Hill Road
Kenilworth, N.J. 07033-0530
Grade IV astrocytoma: The three main forms of treatment for GBM are surgery and radiation or chemotherapy. These treatments may be used alone or in combination with one another. The initial treatment in most cases is surgical excision and removal of as much as the tumor as possible (resection). Often, only a portion of the tumor can be safely removed because malignant cells may have spread to surrounding brain tissue. Because surgery cannot completely remove a tumor, radiation therapy and chemotherapy are used following surgery to continue treatment.
The FDA has approved temozolomide (Temodar) for the treatment of adults with GBM. Temozolomide is used concurrently with radiation therapy, and also for a period of time after completion of radiotherapy. For more information, contact:
Merck Corporate Headquarters
2000 Galloping Hill Road
Kenilworth, N.J. 07033-0530
Gliadel Wafers have been approved by the FDA for the treatment of individuals with newly-diagnosed GBM as an adjunct to surgery and radiation. It has also been approved for individuals with recurrent GBM. Several of the wafers are placed in the cavity created by the surgical removal of a GBM. The wafers release the drugs into the surrounding tissue over a period of two or three weeks. For more information, contact:
MGI Pharma, Inc.
5775 West Old Shakopee Road
Bloomington, MN 55437
Phone: (952) 346-4700
Fax: (352) 346-4800
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government website.
For information about clinical trials being conducted at the National Institutes of Health (NIH) in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
For information about clinical trials sponsored by private sources, contact:
For information about clinical trials conducted in Europe, contact:
Contact for additional information about astrocytoma:
Kenneth D. Aldape, MD
Professor of Pathology
Princess Margaret Cancer Centre
101 College St
Toronto, ON M5G 1L7
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