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Brain Tumors in Children

by David N. Korones, MD

  • The most common brain tumors in children are astrocytomas, medulloblastomas, and ependymomas.

  • Brain tumors can cause various symptoms, including headaches, nausea, vomiting, vision problems, listlessness, and loss of coordination or balance.

  • The diagnosis is usually based on results of magnetic resonance imaging and a biopsy.

  • Treatment may involve surgery, radiation therapy, chemotherapy, or a combination.

Brain tumors (see also see Brain Tumors) are the second most common cancer in children younger than 15 years (after leukemia) and the second leading cause of death from cancer. What causes brain tumors is usually unknown.

Symptoms

The first symptoms may result from increased pressure within the skull (intracranial pressure). Pressure may be increased because the tumor blocks the flow of cerebrospinal fluid within the brain or because the tumor takes up space. Increased pressure can cause the following:

  • An enlarged head (hydrocephalus) in infants and very young children

  • Headaches

  • Nausea and vomiting (often when the child first awakens)

  • Vision problems, such as double vision

  • Difficulty turning the eyes upward

  • Changes in mood or consciousness level, making the child irritable, listless, confused, or drowsy

Other symptoms vary depending on the specific part of the brain in which the tumor is located.

Diagnosis

Doctors suspect a brain tumor based on symptoms. To check for a brain tumor, doctors typically do an imaging test such as magnetic resonance imaging (MRI), which can usually detect the tumor. Before MRI is done, a contrast agent is usually injected into a vein. Contrast agents make the images clearer. If a brain tumor is suspected, a biopsy is done to confirm the diagnosis. Sometimes the tumor is removed at the time of the biopsy.

Sometimes a spinal tap (lumbar puncture—see see Figure: How a Spinal Tap Is Done) is done to obtain cerebrospinal fluid for examination under a microscope. This procedure is done routinely to assess for spread of certain tumors that are known to invade the cerebrospinal fluid or when the diagnosis is unclear.

Treatment

Usually, treatment involves removing the tumor. Then, chemotherapy, radiation therapy, or both (see see Prevention and Treatment of Cancer) are used. Treatment should be planned by a team of experts in treating brain tumors in children.

If the tumor is blocking the flow of cerebrospinal fluid, a small tube (catheter) may be used to drain the cerebrospinal fluid before the tumor is surgically removed. After a local or general anesthetic is used, the tube is inserted through a tiny opening drilled in the skull, and fluid is withdrawn to reduce the pressure within the skull. The tube is connected to a gauge that measures the pressure within the skull. After a few days, the tube is removed or converted to a permanent drain (shunt—see see Hydrocephalus).

When possible, the tumor is removed surgically by opening the skull (called a craniotomy). Some brain tumors can be removed with little or no damage to the brain. After surgery, MRI may be done to determine whether any of the tumor is left and, if so, how much.

If the tumor cannot be removed surgically, additional treatment is usually required. In children younger than 5 to 10 years, depending on the tumor type, chemotherapy may be used first because radiation therapy can interfere with growth and brain development. If needed, radiation therapy may be used when children are older. Chemotherapy may also have serious side effects.

Because cancer is relatively rare in children, entry into a clinical trial (see The Science of Medicine) should be considered for all children with a brain tumor. In such trials, some children receive the standard treatment, and others receive the treatment being tested. The experimental treatment may involve new drugs, drugs used in new ways, or new surgical techniques. However, experimental treatments are not always effective, and side effects or complications may not be known.

Astrocytomas

Astrocytomas develop from star-shaped cells (astrocytes) that help nerve cells in the brain (or spinal cord) function. These tumors may be cancerous or not.

Astrocytomas are the most common brain tumors in children, accounting for up to 50%. These tumors are usually diagnosed between ages 5 and 9 years.

Symptoms and Diagnosis

Pressure within the skull increases, causing headaches (often when children first awaken), vomiting, and listlessness. Children may lose their coordination and have difficulty walking. Vision may be blurred or lost, and the eyes may bulge or involuntarily jerk in one direction, then drift back (nystagmus).

Astrocytomas in the spinal cord may cause back pain, difficulty walking, and muscle weakness.

MRI with a contrast agent is usually done. If it is unavailable, computed tomography (CT) is used, but it is less accurate. Then doctors must take a sample of tissue from the tumor and examine it under a microscope (biopsy) because treatment is based on how abnormal the tumor cells look (the tumor’s grade). These tumors are typically classified as low-grade (for example, juvenile pilocytic astrocytoma), intermediate-grade, or high-grade (for example, glioblastoma).

Treatment

Most low-grade astrocytomas are surgically removed. Sometimes, separating the tumor from normal brain tissue is too difficult, or the tumor is inaccessible. In such cases, radiation therapy is used instead. Radiation therapy is also used if the tumor is likely to impair intellectual functioning or is progressing quickly. If children are younger than 10 years, chemotherapy may be used instead of radiation therapy because it can interfere with growth and brain development in young children. Most low-grade astrocytomas can be cured.

Intermediate-grade astrocytomas are somewhere between low-grade and high-grade astrocytomas. If they look more like high-grade tumors, they are treated more aggressively (radiation and chemotherapy). If they look more like low-grade astrocytomas, they are treated with surgery alone, surgery followed by radiation (older children), or chemotherapy (younger children).

High-grade astrocytomas are treated with a combination of surgery (if possible), radiation therapy, and chemotherapy. The outlook is worse for children with a high-grade tumor, in whom the overall survival is only 20 to 30%.

Ependymomas

Ependymomas are slow-growing tumors that develop from cells lining the spaces within the brain (ventricles).

Ependymomas are the third most common brain tumor in children, accounting for 10%. The majority of children diagnosed with ependymoma are younger than 8 years. About one third of cases occur in children younger than 3 years.

Most ependymomas develop in or near the back of the brain at the bottom of the skull (called the posterior fossa). This area is near the cerebellum (which helps control coordination and balance) and the brain stem (which controls critical body functions such as breathing). Ependymomas tend to spread to the brain stem. Sometimes ependymomas develop in the spinal cord.

Symptoms and Diagnosis

The first symptoms often result from increased pressure within the skull. They include headaches, vomiting, and listlessness. Infants may not meet developmental milestones. They may be irritable and have no appetite. Mood or personality may change, and children may have difficulty concentrating. Children have problems with balance, coordination, and walking. Some children have seizures.

Ependymomas in the spinal cord may cause back pain, and children may have difficulty controlling urination and bowel movements.

The diagnosis is based on results of an MRI and a biopsy.

Prognosis and Treatment

How well children do after treatment depends partly on their age:

  • About 25 to 46% of children aged 4 years and younger survive for 5 years.

  • More than 70% of older children survive for 5 years.

How well children do also depends on how much of the tumor can be removed. Intellectual capacity may be affected in children who survive.

Initial therapy is removal of as much of the tumor as is safely possible. Radiation therapy, chemotherapy, or both are then required.

Medulloblastoma

Medulloblastomas are rapidly growing tumors that develop in the cerebellum (the part of the brain that helps control coordination and balance).

Medulloblastomas account for about 20% of brain and spinal cord cancers in children. The peak incidence is in children 5 to 7 years old, but they can occur in infants and younger children and throughout adolescence. These tumors are more common among boys.

Medulloblastomas develop in the part of the brain that controls coordination and balance (cerebellum), which is located in the back of the brain below the cerebrum. Medulloblastomas tend to spread to other parts of the brain and to the spinal cord. Occasionally, they spread to other parts of the body.

What causes medulloblastomas is unclear. They sometimes occur in people with certain hereditary disorders (such as Gorlin's syndrome or Turcot's syndrome).

Symptoms and Diagnosis

In many children, the first symptom is frequent vomiting. Children may become clumsy, walk unsteadily, or have trouble maintaining their balance. They may have headaches, lethargy, and double vision.

The diagnosis is based on results of MRI with a contrast agent and a biopsy.

Prognosis

How well children do after treatment generally depends on whether they are categorized as having average-risk or high-risk disease. Risk is average if

  • The tumor is at the very back of the brain.

  • All or almost all of the tumor can be removed during surgery.

  • The tumor has not spread to other parts of the body.

Risk is high if

  • The tumor is not at the very back of the brain.

  • Some of the tumor cannot be removed during surgery.

  • The tumor has spread to other parts of the brain, the spinal cord, or elsewhere in the body.

For children older than 3 years, the chances of surviving cancer-free for 5 years is about 80% if the tumor is average-risk and about 50 to 60% if it is high-risk. For children 3 years old and younger, outcome is harder to predict, but overall survival is poor. In about 40% of these children, the tumor has spread. When children are younger, intellectual development is more likely to be affected. For example, they may have difficulty learning, remembering, and making decisions.

Treatment

Medulloblastomas are best treated by removing the tumor and using chemotherapy, radiation therapy, or both. A few children (those younger than 3 years) may be effectively treated with chemotherapy alone.