MedulloblastomaLast Updated: July 31, 2009 This section has been reviewed and approved by the Cancer.Net Editorial Board, 06/09 Overview
Medulloblastoma is a type of brain tumor. A brain tumor begins when normal cells in the brain begin to change and grow uncontrollably, forming a mass. A tumor can be benign (noncancerous) or malignant (cancerous, meaning is can spread to other parts of the body). Medulloblastoma is most often cancerous. The brain and spinal column make up the central nervous system (CNS), where all vital functions are controlled, including thought, speech, and body strength. Medulloblastoma begins in granular cells in the cerebellum (back of the brain). This is the part of the brain that controls body movement and coordination. Medulloblastoma may also be called a primitive neuroectodermal tumor (PNET). Medulloblastoma occurs most commonly in children, and this section is about childhood medulloblastoma. Learn more about CNS tumors in children and brain tumors in adults. Statistics About 15% of childhood central nervous system tumors are medulloblastoma. The overall five-year 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 children ages 0 to 14 with medulloblastoma is 55%. 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 medulloblastoma. Because the survival statistics are measured in five-year intervals, they may not represent advances made in the treatment or diagnosis of this cancer. Source: American Cancer Society. 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 that 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. Doctors don’t know what causes most childhood cancers, including medulloblastoma. Medulloblastoma occurs more often in boys than in girls and most often in the first eight years of life. Half of the tumors occur in children younger than six years old.
Symptoms
Children with medulloblastoma may experience the following symptoms. Sometimes, children with medulloblastoma 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.
If the tumor spreads to the spinal cord, it may cause the following symptoms:
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 tumor 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 medulloblastoma: Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer 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). 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 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. Lumbar puncture (spinal tap). A lumbar puncture is a procedure in which a doctor takes a sample of cerebral spinal fluid (CSF) to look for cancer cells, blood, or tumor markers (substances found in higher than normal amounts in the blood, urine, or body tissues of people with certain kinds of cancer). CSF is the fluid that flows around the brain and the spinal cord. Doctors generally give an anesthetic to numb the lower back before the procedure. 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 its size, 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 cancer’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 cancer. Medulloblastoma in children is classified as either standard (average) risk or high risk, depending on the following factors: the child’s age, how much of the cancer remains after surgery, and whether the tumor has spread. Standard-risk tumor. A standard-risk tumor occurs in children older than age three. The tumor is able to be almost completely removed during surgery, meaning that less than 1.5 cubic centimeters of the tumor remains after surgery. The tumor is in the very back part of the brain and has not spread. High-risk tumor. A high-risk tumor occurs in children of any age. This type of tumor has either spread to other parts of the brain or the spine, or it has not spread but more than 1.5 cubic centimeters of tumor remains after surgery. Recurrent tumor. A recurrent tumor is a tumor that comes back after treatment. It may recur in the brain, spine, or elsewhere in the body. Treatment
In general, cancer in children is uncommon, so it can be hard for doctors to plan treatments unless they know what has been most effective in other children. That’s why more than 60% of children with cancer are treated as part of a clinical trial. Clinical trials are research studies that compare the standard treatments (the best treatments available) with newer treatments that may be more effective. Investigating new treatments involves careful monitoring using scientific methods and all participants are followed closely to track progress. To take advantage of these newer treatments, all children with cancer should be treated at a specialized cancer center. Doctors at these centers have extensive experience in treating children with cancer and have access to the latest research. A doctor who specializes in treating children with cancer is called a pediatric oncologist. Many times, a team of doctors treats a child with cancer. Pediatric cancer centers often have extra support services for children and their families, such as nutritionists, social workers, and counselors. Special activities for kids with cancer may also be available. The treatment of medulloblastoma depends on the size and location of the tumor, whether the cancer has spread, and the child’s overall health. Three types of treatment are typically used to treat medulloblastoma: surgery, radiation therapy, and chemotherapy. Sometimes, the treatments are used in combination. In some situations, stem cell or bone marrow transplantation may be recommended. Descriptions of the most common treatment options for medulloblastoma are listed below. Surgery Surgery is the first treatment most commonly used for medulloblastoma. A neurosurgeon is a doctor who specializes in treating a tumor in the brain or spine with surgery. The goal of medulloblastoma treatment is the complete surgical removal of the tumor. In addition to removing or reducing the size of the tumor, surgery can provide a tissue sample for biopsy analysis, as explained in the Diagnosis section. Surgery to the brain requires the removal of part of the skull, a procedure called a craniotomy. After the surgeon removes the tumor, the patient’s own bone will be used to cover the opening in the skull. There have been rapid advances in surgery for brain tumors, including the use of cortical mapping (which allows doctors to identify certain areas of the brain that control the senses, language, and motor skills) and enhanced imaging devices to give surgeons more tools to plan and perform the surgery. 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. In a cancerous tumor, even if the cancer cannot be cured, its removal can relieve symptoms if it is creating pressure on parts of the brain. Side effects from surgery for medulloblastoma can vary, and patients are encouraged to discuss possible short-term and long-term side effects with their doctor. 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. Because radiation therapy can sometimes interfere with the normal growth and development of the child’s brain and spine, the doctor may choose to treat the tumor in another way. If radiation therapy is recommended, the approach will be based on the child’s age. For children older than age three, radiation therapy includes a moderate dose to the entire brain and spine, followed by a higher dose directly aimed at the tumor bed (the tumor and the surrounding area) or the back part of the brain. For children younger than three years old, radiation therapy may be limited to the back part of the brain, or tumor bed, after surgery and chemotherapy (see below). Side effects from radiation therapy may include fatigue, mild skin reactions, upset stomach, and loose bowel movements. Most side effects go away soon after treatment is finished. Learn more about radiation therapy. 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 regime (schedule) usually consists of a specific number of cycles given over a specific time. Chemotherapy for medulloblastoma may be given by mouth (orally) or by injection into a vein (by IV or intravenously) or muscle. Sometimes, it is delivered directly into the cerebrospinal fluid, which is fluid that circulates around the brain and spinal cord. Researchers are studying ways to use chemotherapy before, during, or after radiation therapy, as the two forms of treatment can be more effective when combined. High-dose chemotherapy may be used before or instead of radiation therapy for children younger than three to four years old. Several cycles of high-dose chemotherapy may be used before or after radiation therapy in children older than three to four years old. High-dose chemotherapy is most effective when there is little tumor left after surgery. 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/bone marrow transplant may be used for children with recurrent medulloblastoma. 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 cells: allogeneic (ALLO) and autologous (AUTO). Only AUTO transplantation is used to treat medulloblastoma. In an AUTO transplant, the patient’s own stem cells are used as the replacement cells. The stem cells are obtained from the patient when he or she is in remission (temporary or permanent disappearance of the signs and symptoms of a tumor but not necessarily the entire disease) 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 medulloblastoma Treatment of recurrent medulloblastoma depends on two factors:
Depending on individual circumstances, the doctor may recommend surgery, radiation therapy, chemotherapy, or stem cell/bone marrow transplantation. High-dose chemotherapy may be a part of “salvage” treatment for children with recurrent medulloblastoma. Salvage chemotherapy refers to the use of chemotherapy for a patient who experiences a recurrence of cancer following initial treatment, in the hope of providing a cure or prolonging life. Find out more about common terms used during cancer treatment. Clinical Trials Resources
Doctors and scientists are always looking for better ways to treat children with medulloblastoma. 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. People decide to participate in clinical trials for many reasons. For some patients, a clinical trial is the best treatment option available. Because standard treatments are not perfect, people are often willing to face the added uncertainty of a clinical trial in the hope of a better result. Other people volunteer for clinical trials because they know that finding new drugs and other therapies is the only way to make progress in treating medulloblastoma. Even if they do not benefit directly from the clinical trial, their participation may benefit future patients with medulloblastoma. 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. In order 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 patient's options, so that 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 than the risks of standard treatment. Finally, the doctor must explain what will be required of each patient 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 medulloblastoma, 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 medulloblastoma, 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 size and location of the tumor, the individual treatment plan (including the length and dosage of treatment), and your 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 medulloblastoma 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 medulloblastoma 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 tumor, including medulloblastoma, 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 need to check for long-term side effects, such as cognitive (thought-process) and endocrine (hormonal) symptoms caused by radiation therapy to the brain or spinal cord, side effects caused by surgery, and the possibility of secondary cancers. 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 cancer 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 cancer treatment is complete. Current Research
Research for medulloblastoma 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 doctor. Improved methods of imaging and surgery. Imaging techniques have been developed that help surgeons pinpoint the tumor’s location, which may reduce or prevent tissue damage to the healthy parts of the brain during treatment.
Improved methods of delivering radiation treatment. Conformal radiation therapy is a way to deliver high doses of radiation therapy more directly to a tumor, avoiding healthy tissue. This technique produces detailed three-dimensional maps of the brain and tumor, so doctors know exactly where to deliver the radiation treatment. Combination of therapies. Other areas of investigation include studies that examine the safety of reducing the doses of radiation therapy for children with a standard-risk tumor using new chemotherapy approaches. Other studies in infants and older children with a high-risk tumor focus on new drugs and combinations of radiation treatment and chemotherapy in the hope of slowing or stopping tumor growth. Questions to Ask the Doctor
Regular communication with your child’s doctor is important in 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. |
