General Information About Childhood Astrocytomas
Key Points for This Section
- Childhood astrocytoma is a disease in which benign (noncancer) or malignant (cancer) cells form in the tissues of the brain.
- The central nervous system controls many important body functions.
- The cause of most childhood brain tumors is not known.
- The symptoms of astrocytomas are not the same in every child.
- Tests that examine the brain and spinal cord are used to detect (find) childhood astrocytomas.
- Childhood astrocytomas are diagnosed and removed in surgery.
- Certain factors affect prognosis (chance of recovery) and treatment options.
Astrocytomas are tumors that start in star-shaped brain cells called astrocytes. An astrocyte is a type of glial cell. Glial cells hold nerve cells in place and help them work the way they should. There are several types of astrocytomas. They can form anywhere in the central nervous system (brain and spinal cord). Brain tumors are the third most common type of cancer in children.
The tumors may be benign (not cancer) or malignant (cancer). Benign brain tumors grow and press on nearby areas of the brain. They rarely spread into other tissues. Malignant brain tumors are likely to grow quickly and spread into other brain tissue. When a tumor grows into or presses on an area of the brain, it may stop that part of the brain from working the way it should. Both benign and malignant brain tumors can cause symptoms and need treatment.
Treatment of metastatic brain tumors is not discussed in this summary. Metastatic brain tumors are formed by cancer cells that begin in other parts of the body and spread to the brain.
Brain tumors can occur in both children and adults. However, treatment for children may be different than treatment for adults. (For more information about the different types of brain tumors, see the PDQ Childhood Brain and Spinal Cord Tumors Treatment Overview summary about children and the Adult Brain Tumors summary about adults.)
Astrocytomas most commonly form in these parts of the central nervous system (CNS):
- Cerebrum: The largest part of the brain, at the top of the head. The cerebrum controls thinking, learning, problem-solving, speech, emotions, reading, writing, and voluntary movement.
- Cerebellum: The lower, back part of the brain (near the middle of the back of the head). The cerebellum controls movement, balance, and posture.
- Brain stem: The part that connects the brain to the spinal cord, in the lowest part of the brain (just above the back of the neck). The brain stem controls breathing, heart rate, and the nerves and muscles used in seeing, hearing, walking, talking, and eating.
- Hypothalamus: The area in the middle of the base of the brain that controls body temperature, hunger, and thirst.
- Visual pathway: The group of nerves that connect the eye with the brain.
- Spinal cord: The column of nerve tissue that runs from the brain stem down the center of the back. It is covered by three thin layers of tissue called membranes. The spinal cord and membranes are surrounded by the vertebrae (back bones). Spinal cord nerves carry messages between the brain and the rest of the body, such as a signal from the brain to cause muscles to move or from the skin to the brain for the sense of touch.
Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. Talk with your child's doctor if you think your child may be at risk. Possible risk factors for astrocytoma include:
- Past radiation therapy to the brain.
- Having certain genetic disorders, such as neurofibromatosis type 1 (NF1).
Having NF1 may increase a child's risk of a type of tumor called visual pathway glioma. These tumors usually do not cause symptoms. Children with NF1 who develop visual pathway gliomas may not need treatment for the tumor unless symptoms, such as vision problems, appear or the tumor grows.
Symptoms are different depending on the following:
- Where the tumor forms in the brain or spinal cord.
- The size of the tumor.
- How fast the tumor grows.
- The child's age and development.
Some tumors do not cause symptoms. Other conditions may cause the same symptoms as those caused by childhood astrocytomas. Check with your child's doctor if you see any of the following problems in your child:
- Morning headache or headache that goes away after vomiting.
- Nausea and vomiting.
- Vision, hearing, and speech problems.
- Loss of balance and trouble walking.
- Worsening handwriting or slow speech.
- Weakness or change in feeling on one side of the body.
- Unusual sleepiness or change in energy level.
- Change in personality or behavior.
- Weight loss or weight gain for no known reason.
- Increase in the size of the head (in infants).
The following tests and procedures may be used:
- Physical exam and history : An exam of the body to check general signs of health. This includes checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
- Neurological exam : A series of questions and tests to check the brain, spinal cord, and nerve function. The exam checks a person’s mental status, coordination, and ability to walk normally, and how well the muscles, senses, and reflexes work. This may also be called a neuro exam or a neurologic exam.
- MRI (magnetic resonance imaging) with gadolinium : A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of the brain and spinal cord. A substance called gadolinium is injected into a vein. The gadolinium collects around the cancer cells so they show up brighter in the picture. This procedure is also called nuclear magnetic resonance imaging (NMRI). Sometimes magnetic resonance spectroscopy (MRS) is done during the same MRI scan to look at the chemical makeup of the brain tissue.
- CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
If doctors think there may be an astrocytoma, a biopsy may be done to remove a sample of tissue. For tumors in the brain, the biopsy is done by removing part of the skull and using a needle to remove tissue. Sometimes, the needle is guided by a computer. A pathologist views the tissue under a microscope to look for cancer cells. If cancer cells are found, the doctor may remove as much tumor as safely possible during the same surgery. Because it can be hard to tell the difference between types of brain tumors, you may want to have your child's tissue sample checked by a pathologist who has experience in diagnosing brain tumors.
The following tests may be done on the tissue that was removed:
- Immunohistochemistry study: A laboratory test in which a substance such as an antibody, dye, or radioisotope is added to a sample of cancer tissue to test for certain antigens. This type of study is used to tell the difference between different types of cancer. An MIB-1 test is a type of immunohistochemistry study that checks tumor tissue for an antigen called MIB-1. This may show how fast a tumor is growing.
- Light and electron microscopy : A laboratory test in which cells in a sample of tissue are viewed under regular and high-powered microscopes to look for certain changes in the cells.
- Cytogenetic analysis : A laboratory test in which cells in a sample of tissue are viewed under a microscope to look for certain changes in the chromosomes.
A biopsy may not be needed for children who have NF1.
- Where the astrocytoma has formed in the CNS and if it has spread.
- Whether there are cancer cells left after surgery.
- The type and grade of astrocytoma.
- Whether the child has NF1.
- Whether there are certain changes in the genes.
- The child’s age.
- Whether the astrocytoma has just been diagnosed or has recurred (come back).
For recurrent astrocytoma, prognosis and treatment depend on how long it was from the time treatment ended to the time the astrocytoma recurred.