Childhood Medulloblastoma

by National Cancer Institute

Childhood medulloblastoma is a disease in which benign (noncancer) or malignant (cancer) cells form in the tissues of the brain.

Childhood medulloblastoma (tumor) usually forms in the cerebellum, which is at the lower back of the brain. The cerebellum is the part of the brain that controls movement, balance, and posture. Childhood medulloblastoma may also be called primitive neuroectodermal tumor (PNET).

About 1 out of 5 childhood brain tumors are medulloblastomas. Although cancer is rare in children, brain tumors are the most common type of childhood cancer other than leukemia and lymphoma.

This summary refers to the treatment of primary brain tumors (tumors that begin in the brain). Treatment for metastatic brain tumors, which are tumors formed by cancer cells that begin in other parts of the body and spread to the brain, is not discussed in this summary.

Brain tumors can occur in both children and adults; however, treatment for children may be different than treatment for adults.

The cause of most childhood brain tumors is unknown.

The signs of childhood medulloblastoma vary and often depend on the child's age and where the tumor is located.

These symptoms may be caused by a medulloblastoma or other conditions. A doctor should be consulted if any of the following problems occur:

• Loss of balance, difficulty walking, worsening handwriting, or slow speech.
• Morning headache or headache that goes away after vomiting.
• Nausea and vomiting.
• Unusual sleepiness or change in energy level.
• Change in personality or behavior.
• Unexplained weight loss or weight gain.

Tests that examine the brain and spinal cord are used to detect (find) childhood medulloblastoma.

The following tests and procedures may be used:

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.

MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the brain and spinal cord. A substance called gadolinium is injected into the patient through 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).

Childhood medulloblastoma is diagnosed and removed in surgery.

If a brain tumor is suspected, a biopsy is done by removing part of the skull and using a needle to remove a sample of the tumor tissue. A pathologist views the tissue under a microscope to look for cancer cells. If cancer cells are found, the doctor will remove as much tumor as possible during the same surgery.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis (chance of recovery) and treatment options depend on:

• The age of the child when the tumor is found.
• The location of the tumor.
• The amount of tumor remaining after surgery.
• Whether the cancer has spread to other parts of the central nervous system (brain and spinal cord), or to other parts of the body, such as the bones.

Stages of Childhood Medulloblastoma

After childhood medulloblastoma has been diagnosed, tests are done to find out if there is tumor remaining or if cancer cells have spread.

The extent or spread of cancer is usually described as stages. For childhood medulloblastoma, risk groups are used instead of stages. Risk groups are described by the amount of remaining tumor or spread of cancer cells within the central nervous system (brain and spinal cord) or to other parts of the body. It is important to know the risk group in order to plan treatment. The following tests and procedures may be used to determine the risk group:

MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the brain and spinal cord. A substance called gadolinium is injected into the patient through 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).

Lumbar puncture: A procedure used to collect cerebrospinal fluid from the spinal column. This is done by placing a needle into the spinal column. This procedure is also called an LP or spinal tap.

Bone marrow biopsy: The removal of a small piece of bone and bone marrow by inserting a needle into the hipbone or breastbone. A pathologist views both the bone and the bone marrow samples under a microscope to look for signs of cancer.

Bone scan: A procedure to detect if there are rapidly dividing cells, such as cancer cells, in the bone. A very small amount of radioactive material is injected into a vein and travels through the blood stream. The radioactive material collects in the bones and is detected by a scanner.

The following risk categories are used for childhood medulloblastoma:

Average risk

Childhood medulloblastoma is called an average risk if all of the following are true:

• The child is older than 3 years of age.
• The tumor is at the very back of the brain.
• All of the tumor was removed by surgery or there was a very small amount remaining.
• The cancer has not spread to other parts of the body.

Poor risk

Childhood medulloblastoma is called a poor risk if any of the following are true:

• The child is younger than 3 years of age.
• The tumor is not at the very back of the brain.
• Some of the tumor was not removed by surgery.
• The cancer has spread to other parts of the body.

In general, cancer is more likely to recur (come back) in patients in the poor risk group.

Recurrent Childhood Medulloblastoma

Recurrent childhood medulloblastoma is a tumor that has recurred (come back) after it has been treated. Childhood medulloblastoma often recurs. A tumor may come back many years later at the same place or a different place in the brain. It can also come back in other parts of the body such as the spinal cord.

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