Central Nervous System - ChildhoodLast Updated: July 24, 2009 This section has been reviewed and approved by the Cancer.Net Editorial Board, 06/09 Overview
A central nervous system (CNS) tumor begins when normal cells in the brain or the spinal cord begin to change and grow uncontrollably, forming a mass. A tumor can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body). The brain is the center of thought, memory, and emotion. It controls the five senses (smell, touch, taste, hearing, and sight), movement, and other basic functions of the body, including heartbeat, circulation, and breathing. The spinal cord consists of nerves that carry information back and forth between the body and the brain. A tumor located in the CNS is especially problematic because a person’s thought processes and movements can be affected. This type of tumor also may be challenging to treat because the tissues surrounding the tumor may be vital to the body’s functioning. Anatomy of the brain The brain is composed of four major parts: the cerebrum, cerebellum, brain stem, and meninges. The cerebrum, the largest part of the brain, contains two cerebral hemispheres and is divided into four lobes where specific functions occur.
The cerebellum, or "little brain," is located beneath the cerebrum. The cerebellum controls coordination and balance. The brain stem, which is the lowest portion of the brain and connects to the spinal cord, controls involuntary functions essential for life, such as heartbeat and breathing. The meninges are the membranes that surround and protect the brain and spinal cord. There are three meningeal layers, called the dura mater, arachnoid, and pia arachnoid. Types of CNS tumors There are many different types of CNS tumors. Some are cancerous and very likely to grow and spread (called very aggressive or high grade), others are less aggressive (low grade), and others are noncancerous, which means they are not likely to grow and spread. The following types of CNS tumors are most common among children: Statistics Approximately 3,400 CNS tumors are diagnosed each year in children under the age of 20. About 850 of these are considered benign (non-cancerous) tumors. CNS tumors are the second most common childhood cancer, after leukemia. The overall five-year relative survival rate (the percentage of people who survive at least five years after the cancer is detected, excluding those who die from other diseases) for CNS tumors is 74%. Cancer survival statistics should be interpreted with caution. These estimates are based on data from thousands of cases of this type of cancer, but the actual risk for a particular individual may differ. It is not possible to tell a person how long he or she will live with a CNS tumor. Because the survival statistics are measured in five-year intervals, they may not represent advances made in the treatment or diagnosis of this cancer. Statistics adapted from the American Cancer Society's publication, Cancer Facts and Figures 2009. Find out more about basic cancer terms used in this section. Medical Illustrations
Risk Factors
A risk factor is anything that increases a person’s chance of developing a tumor. Some risk factors can be controlled, such as smoking, and some cannot be controlled, such as age and family history. Although risk factors can influence the development of a tumor, most do not directly cause a tumor. Some people with several risk factors never develop a tumor, while others with no known risk factors do. The cause of a CNS tumor in children is not known. Researchers are studying a variety of possible causes of CNS tumors, including viruses. Different types of CNS tumors occur in different age groups. For example, some types of CNS tumors are more common in children under age three. Head injury does not appear to cause a CNS tumor. A small number of CNS tumors occur in families. However, only a small percentage of children with a brain tumor have identifiable genetic causes, usually in association with a familial disease called neurofibromatosis. Neurofibromatosis is an inherited disorder that causes neurofibromas (noncancerous tumors) to form on peripheral nerves in the body, brown spots on the skin, and deformities of tissues and bones. Neurofibromatosis is also called Recklinghausen’s disease or von Recklinghausen’s disease. Learn more about neurofibromatosis Type 1 and neurofibromatosis Type 2. Other, less common genetic conditions associated with a higher risk of a CNS tumor include Li-Fraumeni syndrome, tuberous sclerosis, nevoid basal cell syndrome, and Turcot syndrome. Symptoms
Children with a CNS tumor may experience the following symptoms. Sometimes, children with a CNS tumor do not show any of these symptoms. Or, these symptoms may be caused by a medical condition that is not a tumor. If you are concerned about a symptom on this list, please talk with your child’s doctor. The symptoms of a CNS tumor depend on where the tumor is located and can affect any of the brain’s functions. The following symptoms may indicate the presence of a CNS tumor:
In a baby, the only symptom may be that the head is growing too fast. An infant’s skull can expand to make room for a growing tumor, so the baby may have a larger than normal head. Diagnosis
Doctors use many tests to diagnose a tumor and determine if it has metastasized (spread). Some tests may also determine which treatments may be the most effective. For most types of tumors, a biopsy is the only way to make a definitive diagnosis of cancer. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis. Imaging tests may be used to find out whether the cancer has metastasized. Your doctor may consider these factors when choosing a diagnostic test:
In addition to a physical examination, the following tests may be used to diagnose a CNS tumor: Computed tomography (CT or CAT) scan. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a patient’s vein to provide better detail. Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A contrast medium may be injected into a patient’s vein to create a clearer picture. Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that a tumor is present, but only a biopsy can make a definite diagnosis. The sample removed during the biopsy is analyzed by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease). The type of biopsy performed depends on the location of the tumor. Learn more about what to expect when having common tests, procedures, and scans. Find out more about common terms used during a diagnosis of cancer. Staging
Staging is a way of describing a tumor, such as where it is located, if or where it has spread, and if it is affecting the functions of other organs in the body. Doctors use diagnostic tests to determine the tumor's stage, so staging may not be complete until all of the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient’s prognosis (chance of recovery). There are different stage descriptions for different types of tumors. Several types of childhood CNS tumors can spread through the spinal fluid that surrounds the brain and the spine. For most types of CNS tumors, the tumor is described as either high-grade or low-grade, depending on how much of the tumor is left after surgery, the child’s age, and whether the tumor has spread. In general, a child with a low-grade tumor has a better prognosis. A recurrent tumor is a tumor that comes back after treatment. Read more about staging for a specific type of CNS tumor. For example, review the staging section under astrocytoma, if that is the specific diagnosis. Treatment
The treatment of a CNS tumor depends on the type of CNS tumor, the size and location of the tumor, whether it is cancerous, whether the cancer has spread, and the age of the child. Radiation therapy is often limited in children younger than three years old, because extensive radiation therapy can cause learning and memory problems later on in the child’s life.
Descriptions of the most common treatment options for a CNS tumor are listed below. Surgery Surgery is almost always used to determine the type of tumor, either through a biopsy or during treatment when the tumor can be removed without significant damage to the brain. A neurosurgeon is a doctor who specializes in treating a tumor in the brain or spine with surgery. The goal of brain tumor treatment is complete surgical removal of the tumor. Sometimes, a tumor spreads and grows between normal nerve cells, making surgery difficult. In certain cases, surgery can damage parts of the brain near the tumor, affecting arm and leg movement, breathing, swallowing, eye movement, or consciousness. Some tumors cannot be removed by surgery because of their location; these tumors are called inoperable; in these cases, the doctor will recommend other treatment options. Learn more about cancer surgery. Radiation therapy Radiation therapy is the use of high-energy x-rays or other particles to kill cancer cells. A doctor who specializes in giving radiation therapy to treat cancer is called a radiation oncologist. The most common type of radiation treatment is called external-beam radiation therapy, which is radiation given from a machine outside the body. When radiation treatment is given using implants, it is called internal radiation therapy or brachytherapy. Stereotactic radiosurgery is a way to deliver high doses of radiation therapy directly to a tumor and not to healthy tissue. This technique produces detailed, three-dimensional maps of the brain and tumor, so doctors can pinpoint where to deliver the radiation treatment. It works best for certain noncancerous tumors and a tumor that is only in one area of the brain. Learn more about radiation therapy. Side effects from radiation therapy may include fatigue, mild skin reactions, upset stomach, headaches, and loose bowel movements. Most side effects go away soon after treatment is finished. However, in the long term radiation therapy can sometimes interfere with the normal growth and development of the child’s brain, so the doctor may choose to treat the tumor in another way. Chemotherapy Chemotherapy is the use of drugs to kill cancer cells. Systemic chemotherapy is delivered through the bloodstream, targeting cancer cells throughout the body. Chemotherapy is given by a medical oncologist, a doctor who specializes in treating cancer with medication. Some people may receive chemotherapy in their doctor’s office; others may go to the hospital. A chemotherapy regimen (schedule) usually consists of a specific number of cycles given over a specific time. Chemotherapy is effective for many cancerous types of brain tumors. Depending on the tumor type, chemotherapy may be given immediately after a biopsy or surgery or following radiation therapy. In some instances, chemotherapy is used at the same time as radiation therapy. Chemotherapy may also be given directly into the spinal canal, in a procedure called intrathecal chemotherapy, to treat cancer cells on the surface of the brain and spine. This procedure is still being investigated in clinical trials and may not be widely available. The side effects of chemotherapy depend on the individual and the dose used, but can include fatigue, risk of infection, nausea and vomiting, loss of appetite, and diarrhea. These side effects usually go away once treatment is finished. Learn more about chemotherapy and preparing for treatment. The medications used to treat cancer are continually being evaluated. Talking with your child’s doctor is often the best way to learn about the medications prescribed for your child, their purpose, and their potential side effects or interactions with other medications. Learn more about your child’s prescriptions by using searchable drug databases. Stem cell transplantation/bone marrow transplantation A stem cell transplantation/bone marrow transplantation may be used if a CNS tumor recurs. A stem cell transplant is a medical procedure in which diseased bone marrow is replaced by highly specialized cells, called hematopoietic stem cells. Hematopoietic stem cells are found both in the bloodstream and in the bone marrow. Today, this procedure is more commonly called a stem cell transplant, rather than bone marrow transplant, because blood stems cells are typically what is being transplanted, not the actual bone marrow tissue. There are two types of stem cell transplantation depending on the source of the replacement blood stem cell: allogeneic (ALLO) and autologous (AUTO). AUTO transplantations are used to treat a CNS tumor. In an AUTO transplant, the patient’s own stem cells are used as the replacement cells, instead of cells from a donor. The stem cells are obtained from the patient when he or she is in remission from previous treatment. The stem cells are frozen until they are needed, usually after the high-dose treatment (explained below) is completed. The goal of transplantation is to destroy cancer cells in the marrow, blood, and other parts of the body and have replacement blood stem cells create healthy bone marrow. In most stem cell transplants, the patient is treated with high doses of chemotherapy and/or radiation therapy to destroy as many cancer cells as possible. This also destroys the patient’s bone marrow tissue and suppresses the patient’s immune system. After the high-dose treatment is given, blood stem cells are infused into the patient’s vein to replace the bone marrow and restore normal blood counts. Before recommending transplantation, doctors will talk with the patient about the risks of this treatment and consider several other factors, such as the type of cancer, results of any previous treatment, and patient’s age and general health. In stem cell transplantation, replacement cells engraft (begin to make new blood cells) and turn into healthy, blood-producing tissue in 10 days to three weeks. Destroying the patient’s own marrow reduces the body’s natural defenses, temporarily leaving the patient at an increased risk of infection. Until the patient’s immune system is back to normal, patients may need antibiotics and blood transfusions. In an AUTO transplant, there is little risk of tissue rejection because the replacement stem cells are the patient’s own cells. However, there is a risk in an autologous transplant that some of the cells that are put back into the patient could still be cancerous. Learn more about bone marrow and stem cell transplantation. Recurrent CNS tumor If a CNS tumor comes back after initial treatment, the next phase of treatment depends on three factors:
Depending on individual circumstances, the doctor may recommend surgery, radiation therapy, chemotherapy, and/or stem cell transplantation. Find out more about common terms used during treatment. Clinical Trials Resources
Doctors and scientists are always looking for better ways to treat children with a CNS tumor. A clinical trial is a way to test a new treatment to prove that it is safe, effective, and possibly better than a standard treatment. The clinical trial may be evaluating a new drug, a new combination of existing treatments, a new approach to radiation therapy or surgery, or a new method of treatment or prevention. Children who participate in clinical trials are among the first to receive new treatments before they are widely available. However, there is no guarantee that the new treatment will be safe, effective, or better than a standard treatment. Patients decide to participate in clinical trials for many reasons. For some children, a clinical trial is the best treatment option available. Because standard treatments are not perfect, patients are often willing to face the added uncertainty of a clinical trial in the hope of a better result. Other patients volunteer for clinical trials because they know that finding new drugs and other therapies is the only way to make progress in treating a childhood CNS tumor. Even if they do not benefit directly from the clinical trial, their participation may benefit future patients with a childhood CNS tumor. Sometimes people have concerns that, by participating in a clinical trial, they may receive no treatment by being given a placebo or a “sugar pill”. The use of placebos in cancer clinical trials is rare. When a placebo is used in a study, it is done with the full knowledge of the participants. Find out more about placebos in cancer clinical trials. To join a clinical trial, parents and children must participate in a process known as informed consent. During informed consent, the doctor should list all of the options, so the person understands how the new treatment differs from the standard treatment. The doctor must also list all of the risks of the new treatment, which may or may not be different from the risks of standard treatment. Finally, the doctor must explain what will be required of each person in order to participate in the clinical trial, including the number of doctor visits, tests, and the schedule of treatment. Learn more about clinical trials, including patient safety, phases of a clinical trial, deciding to participate in a clinical trial, questions to ask the research team, and links to find cancer clinical trials. For specific topics being studied for CNS tumors, learn more in the Current Research section. Side Effects
A tumor and its treatment can cause a variety of side effects. However, doctors have made major strides in recent years in reducing pain, nausea and vomiting, and other physical side effects of treatments. Many treatments used today are less intensive but as effective as treatments used in the past. Doctors also have many ways to provide relief to patients when such side effects do occur. Fear of treatment side effects is common after a diagnosis of a tumor, but it may be helpful to know that preventing and controlling side effects is a major focus of your child’s health-care team. Before treatment begins, talk with your child’s doctor about possible side effects of the specific treatments your child will be receiving. The specific side effects that can occur depend on a variety of factors, including the type of tumor, its location, the individual treatment plan (including the length and dosage of treatment), and the child’s overall health. Ask your child’s doctor which side effects are most likely to happen (and which are not), when side effects are likely to occur, and how they will be addressed by the health-care team if they do happen. Also, be sure to communicate with the doctor about side effects your child experiences during and after treatment. Learn more about the most common side effects of a tumor and different treatments, along with ways to prevent or control them. In addition to physical side effects, there may be psychosocial (emotional and social) effects as well. Learn more about the importance of addressing such needs, including concerns about managing the cost of medical care. Learn more about late effects or long-term side effects by reading the After Treatment section or talking with your child’s doctor. After Treatment
After treatment for a CNS tumor ends, talk with your child’s doctor about developing a follow-up care plan. This plan may include regular physical examinations and/or medical tests to monitor your child’s recovery for the coming months and years. All children treated for a CNS tumor should have life-long, follow-up care. Based on the type of treatment the child received, the doctor will determine what examinations and tests are needed to check for long-term side effects and the possibility of secondary cancers. For example, craniospinal (head and spine) radiation therapy can cause cognitive (thought-process) and endocrine (hormonal) symptoms over time, although the severity can vary greatly depending on the dose given and the age of the child. Similarly, the risks and potential side effects of surgery vary widely, depending on the location of the tumor and how it grew. Likewise, the risks of chemotherapy and the likelihood of secondary cancers also strongly depend on the drugs and doses used. Your child’s doctor can recommend the necessary screening tests. Follow-up care should also address the child’s quality of life, including any developmental or emotional concerns. Learn more about childhood cancer survivorship. The child’s family is encouraged to organize and keep a record of the child’s medical information, so that as the child enters adulthood, he or she has a clear, written history of the diagnosis and details of the treatment given. The doctor’s office can help you compile this, and it should include recommendations from the doctor about the schedule for follow-up care. This information will be valuable to doctors who care for your child during his or her lifetime. Children who have had a CNS tumor can also enhance the quality of their future by following established guidelines for good health into and through adulthood, including not smoking, maintaining a healthy weight, eating a balanced diet, and participating in regular physical activity. Talk with the doctor about developing a plan that is best for your child’s needs. Find out more about common terms used after treatment is complete. Current Research
Research for childhood CNS tumors is ongoing. The following advances may still be under investigation in clinical trials and may not be approved or available at this time. Always discuss all diagnostic and treatment options with your child’s doctor. New medications. Doctors are examining new types of drugs that may better control tumor growth. Improved imaging techniques. Imaging techniques are being developed that help surgeons pinpoint the tumor's location, to reduce or prevent tissue damage to the healthy parts of the brain during treatment.
Improved methods of delivering radiation treatment. Doctors are experimenting with new techniques for delivering radiation therapy to certain types of tumors. These methods produce detailed, three-dimensional maps of the brain and tumor, so doctors can reduce radiation given to healthy tissue and focus on the tumor. This can reduce a child’s exposure to radiation and lessen the long-term effects in the child. Use of biologic markers to characterize tumors. Doctors are looking at various proteins and DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) markers in blood samples and tumor tissue of children with cancer to help predict the aggressiveness of a tumor. This information may help doctors treat the tumor more effectively. Questions to Ask the Doctor
Regular communication with your child’s doctor is important for making informed decisions about his or her health care. Consider asking the following questions of your child’s doctor:
Patient Information Resources
In addition to Cancer.Net, there are other sources of information about this type of cancer available online. Cancer.Net maintains a list of national, not-for-profit organizations that may be helpful in finding additional information, services, and support. As always, be sure to talk with your doctor about questions you may have about information you find about this disease. View organizations that offer information on this specific type of cancer. |
