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Medulloblastoma is the most common malignant brain tumor in children. It begins in the cerebellum, an area in the back of the brain.
About 500 new cases of pediatric medulloblastoma are diagnosed every year in the United States. Medulloblastoma accounts for 20% of childhood central nervous system tumors.
Medulloblastoma is most common in children under 16. Children ages 5–9 are diagnosed the most often. Older teens and adults can be diagnosed with it, too.
Medulloblastoma is divided into 4 subgroups. These groups are based on molecular features of tumor cells:
The tumor’s subgroup affects the prognosis. The care team uses subgroups to class patients into risk categories. These details help the care team plan treatments.
Treatment for medulloblastoma can include:
Medulloblastomas are fast growing. These tumors often spread to other parts of the brain and spinal cord.
The overall survival rate for childhood medulloblastoma in the United States is 70–80% if the disease has not spread. If the disease has spread, the survival rate is about 60%.
Signs and symptoms of medulloblastoma depend on several factors. They include the size and location of the tumor and the child’s age and stage of development.
Medulloblastoma symptoms include:
If the tumor has spread to the spinal cord, symptoms may include:
Medulloblastoma is a cerebellar tumor. The cerebellum is in the lower rear part of the brain in a region known as the posterior fossa. Functions of the cerebellum include:
Most medulloblastomas form in the middle of the cerebellum by the 4th ventricle (see image above). As the tumor grows, it can block the flow of the brain fluid called cerebrospinal fluid. This causes a buildup of fluid within the brain called hydrocephalus.
The fluid increases pressure on the brain. Many symptoms of medulloblastoma are due to fluid buildup.
Certain factors can increase the risk of medulloblastoma.
Doctors evaluate medulloblastoma in several ways.
Medulloblastoma is classed or described based on disease risk and prognosis. To help plan treatments, the doctors look at:
Histology looks at features such as size and shape of the tumor cells to class medulloblastoma tumors:
Anaplastic and large cells often appear together. They are grouped as large cell anaplastic (LCA) tumors.
Based on the tumor’s molecular features, medulloblastoma groups include:
The tumor’s location within the cerebellum can also provide a clue as to its molecular type. WNT medulloblastoma tumors tend to occur along the midline of the cerebellum. SHH medulloblastoma tumors tend to be found in the side parts of the cerebellum.
Medulloblastoma may also be classed by metastasis, or spread of disease:
Medulloblastoma treatment includes:
Risk-based approaches to medulloblastoma treatment classify patients based on tumor features and predicted outcomes. Doctors consider:
The goal of a risk-based approach is to cure the disease while lowering the risk of side effects due to treatments.
For patients who are predicted to have good outcomes, lower-intensity therapy can reduce long-term problems from radiation and chemotherapy. For high-risk patients, more intensive therapy can improve chance of survival.
Patients may be offered treatment within a clinical trial.
Surgery is a main treatment for medulloblastoma. The goal is gross total resection, or complete removal of the tumor. In many cases, most or all of the tumor can be removed with surgery. But in some cases, the location of the tumor may limit how much can be removed safely.
Posterior fossa syndrome is a condition that sometimes develops after surgery to remove a tumor in the posterior fossa region of the brain. You might also hear this called cerebellar mutism. Children with this syndrome may have problems with talking, movement, and mood. The risk for posterior fossa syndrome is lower when an experienced neurosurgeon performs the surgery.
Radiation therapy is usually used after medulloblastoma surgery. The dose of radiation therapy depends on the stage of disease and the patient’s risk category. In general, radiation targets the brain and spine (craniospinal irradiation) with a higher dose (boost) at the primary tumor site. Because of the potential health risks, radiation therapy is not used in very young children.
Doctors may use newer types of radiation therapy such as proton beam radiation to treat medulloblastoma. In this type of radiation therapy, the amount of energy and how far it goes into the tumor can be tailored to match the tumor size and shape. This allows doctors to aim high doses of radiation at the tumor, reducing damage to nearby healthy cells. Not every treatment center offers proton therapy.
Chemotherapy is usually used along with radiation therapy and surgery to treat medulloblastoma. In very young children, chemotherapy may be used to help delay radiation until the child is older. High-dose chemotherapy may also be used.
A combination of chemotherapy medicines is used to treat medulloblastoma.
Targeted therapies work by acting on, or targeting, specific features of tumor cells. In some tumors, there are changes in the genes and proteins that control tumor cell growth and division.
Scientists are testing drugs to see if they can block the signals that cause certain types of cancer cells to grow. Your child’s care team may suggest targeted therapy as a treatment option if it could help treat your child’s disease.
The SHH subgroup is the most common type of medulloblastoma in children under age 3. Group 3 tumors are the second most common.
SHH tumors in infants tend to have a favorable histology and molecular profile. Some of these children do well with surgery and chemotherapy without radiation.
Non-SHH medulloblastoma in infants is harder to treat, especially if the disease has spread.
Treatments such as focal radiation therapy and high-dose chemotherapy may be tried. But the prognosis is usually poor. Young children with high-risk medulloblastoma may have side effects that outweigh the possible benefits of treatment.
The overall survival rate for childhood medulloblastoma in the United States is 70–80% if the disease has not spread. If the disease has spread, the survival rate is about 60%. Your child’s care team is the best source of information about your child’s case.
Prognosis for medulloblastoma depends on many factors.
|WNT subtype||SHH subtype||Group 3||Group 4|
|% of Cases||10% of medulloblastomas||30% of medulloblastomas||25% of medulloblastomas||35% of medulloblastomas|
|Patient Characteristics||Most common in older children and teens; rare in infants||Most common in young children under age 3 and in older teens and adults||Most common in infants and young children; rare in teens; more common in males||Found in all age groups but rare in infants; more common in males|
|Medulloblastoma Histology||• Classic (most often)
• Large Cell Anaplastic (rare)
|• Desmoplastic / nodular
• Large cell anaplastic
• Large cell anaplastic
• Large cell anaplastic (rare)
|Metastasis at Diagnosis||5–10% of patients have metastatic disease at diagnosis||15–20% of patients have metastatic disease at diagnosis||30–45% of patients have metastatic disease at diagnosis||35–40% of patients have metastatic disease at diagnosis|
|Recurrence||Rarely recurs||If it recurs, it is usually local disease||If it recurs, it is usually metastatic||If it recurs, it is usually metastatic|
|5-year Survival Rates for Medulloblastoma||>90% survival||75% survival||50% survival||75% survival|
|Overall Medulloblastoma Prognosis||Very good||Intermediate, but infants have a better prognosis||Poor||Intermediate|
Medulloblastoma survivors can have a variety of treatment-related problems. Ongoing follow-up care, lab tests, and routine MRI scans can monitor patients after treatment.
Monitoring should focus on early detection of recurrence (cancer coming back) as well as long-term and late effects of treatment. Care should also include rehabilitation and neurological consultation. Your child’s care team can help you decide the best plan for your child.
Childhood cancer survivors should have long-term follow-up health care. Some treatments can cause late effects. These are health problems that happen months or years after treatment has ended.
It is important to have regular checkups and screenings by a primary health care provider. Your child should get a survivorship care plan after completing treatment. It includes guidance on health screenings, disease risk factors, and ways to improve health.
Survivors should share this plan with their health care providers.
For general health and disease prevention, cancer survivors should adopt healthy habits to protect their health, including physical activity and healthy eating.
Medulloblastoma survivors have an increased risk of late effects, depending on their treatments.
These problems may include:
Children treated for medulloblastoma may have future problems in areas of daily life such as school, work, and relationships. They may also have lower physical fitness and physical function.
Reviewed: May 2023