Medulloblastoma is the most common malignant brain tumor in children. It begins in the cerebellum, an area in the back of the brain. Medulloblastoma can spread to other parts of the central nervous system (brain and spinal cord).
Medulloblastoma is a brain tumor that begins in the cerebellum. The cerebellum is in a part of the brain called the posterior fossa.
About 500 new cases of pediatric medulloblastoma are diagnosed every year in the United States.
In most cases, the cause of medulloblastoma is unknown. But a small number are caused by gene changes that can be passed down in families.
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 main groups, with many subgroups. These groups are based on molecular features of tumor cells:
WNT-activated (pronounced “wint”)
Sonic Hedgehog (SHH)-activated
Group 3 (non-WNT/non-SHH)
Group 4 (non-WNT/non-SHH)
The tumor’s group affects the treatment and prognosis. So, your child's tumor needs molecular testing for an accurate diagnosis.
Treatment for medulloblastoma can include:
Surgery to remove as much of the tumor as possible
Radiation therapy after surgery to destroy any remaining cancer cells
Chemotherapy along with surgery and radiation therapy
Medulloblastoma is divided into 4 main subgroups based on molecular features of tumor cells. The WNT subtype makes up 10% of cases, and the SHH subtype makes up 30% of cases. Group 3 makes up 25% of cases, and Group 4 makes up 35% of cases.
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% (7–8 of 10) if the disease has not spread. If the disease has spread, the survival rate is about 60% (6 of 10).
Symptoms of medulloblastoma
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:
Headache, which is often worse in the morning or improves after vomiting
Nausea and vomiting
Tiredness or changes in activity levels
Dizziness
Loss of balance, clumsiness
Handwriting problems
Vision changes
If the tumor has spread to the spinal cord, symptoms may include:
Back pain
Problems walking
Problems urinating or change in bowel function
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:
Movement control
Balance
Posture
Coordination
Most medulloblastomas form in the middle of the cerebellum by the 4th ventricle. 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.
Risk factors for medulloblastoma
Certain factors can increase the risk of medulloblastoma.
Certain gene and chromosome changes within the tumor cell. Experts usually do not know why these genetic changes occur.
Most medulloblastomas occur in children ages 5–9. These tumors are rare in infants and adults.
Medulloblastoma is slightly more common in boys than in girls. Some children may be at increased risk for brain tumors due to rare inherited conditions or genetic disorders such as:
Lumbar puncture after surgery to look for cancer cells in the cerebrospinal fluid (CSF). About 1/3 of medulloblastomas spread through the CSF to other parts of the brain or spinal cord.
Medulloblastoma is classified or described based on disease risk and prognosis. To help plan treatments, the doctors look at:
Molecular groups (based on gene changes)
Histology (studying tissues and cells under a microscope)
Metastasis (spread of cancer)
Molecular groups
The molecular groups of medulloblastoma are:
WNT-activated
Sonic Hedgehog (SHH)-activated
Group 3 (non-WNT/non-SHH)
Group 4 (non-WNT/non-SHH)
These types are further divided into subgroups:
WNT-activated: No subgroups
SHH-activated: SHH-1, SHH-2, SHH-3, SHH-4
Group 3 and Group 4 medulloblastoma (non-WNT/non-SHH): G3/G4- I, G3/G4-2, G3/G4-3, G3/G4-4, G3/G4-5, G3/G4-6, G3/G4-7, G3/G4-8
Molecular testing must take place to get the correct diagnosis. This will help the doctor create the best treatment plan for your child.
Histology
Histology looks at the size and shape of the tumor cells to class medulloblastoma tumors. This information is considered along with molecular testing.
Histologic groups include:
Medulloblastoma classic: These tumors mostly belong to WNT and group 4 categories. But some group 3 and SHH tumors can have classic histology.
Medulloblastoma large cell anaplastic: These tumors mostly belong to group 3 and SHH-activated tumors.
Medulloblastoma desmoplastic nodular: These tumors are almost always SHH-activated.
Medulloblastoma with extensive nodularity: These tumors are almost always SHH-activated.
Metastasis
Medulloblastoma may also be classified by metastasis, or spread of disease:
M0: The tumor is localized with no spread of disease.
M1: Tumor cells are found in the CSF.
M2: There is evidence of spread of disease within the brain (intracranial).
M3: The tumor has spread to the spine.
M4: The tumor has spread outside the central nervous system (CNS). Common sites for metastases (cancer that has spread) include the bones, lungs, and liver.
Radiation to the brain and spine (unless your child is under age 3)
Risk-based approaches to medulloblastoma treatment classify patients based on tumor features and predicted outcomes. Doctors consider:
Molecular group and subgroup
Whether surgery completely removed the tumor
Whether the tumor has spread
Tumor histology (what it looks like under the microscope)
Age at diagnosis
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 the chance of survival.
Patients may be offered treatment within a clinical trial.
Surgery
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 after medulloblastoma surgery
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. It is important to find a neurosurgeon who has done many such surgeries.
Radiation therapy
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 children under age 3.
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
Chemotherapy is usually used along with radiation therapy and surgery to treat medulloblastoma. In children under age 3, 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 therapy
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 can help treat your child’s disease.
Medulloblastoma in infants
SHH-activated medulloblastoma 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.
Medulloblastoma prognosis
The overall survival rate for childhood medulloblastoma in the United States is 70–80% (7–8 of 10) if the disease has not spread. If the disease has spread, the survival rate is about 60% (6 of 10). Your child’s care team is the best source of information about your child’s case.
Prognosis for medulloblastoma depends on many factors.
Factors that affect chance of medulloblastoma cure
Medulloblastoma histology
Children under age 3: Desmoplastic tumors are linked to better outcomes than classic or LCA tumors.
Children over age 3: Desmoplastic or classic tumors are linked to better outcomes than large cell anaplastic (LCA) tumors.
Molecular subtype. Features of the tumor and changes in genes or chromosomes including medulloblastoma subtype (WNT, SHH, Group 3, or Group 4) influence risk category. WNT tumors have a better prognosis. SHH and Group 4 medulloblastoma tumors are considered intermediate risk. Group 3 medulloblastoma tumors have a worse prognosis.
Whether the cancer has spread. Medulloblastoma that has spread to other parts of the brain or spinal cord is harder to treat. Localized medulloblastoma (medulloblastoma that has not spread) is linked to a better prognosis.
If surgery can completely remove the tumor. Children who have no visible tumor after surgery (gross total resection) have a better chance of cure.
Age at diagnosis. The influence of age on medulloblastoma prognosis depends on the medulloblastoma subgroup and other features. Radiation therapy is not usually used in infants and children under age 3.
If the cancer is new or if it has come back. Recurrent medulloblastoma is linked to worse outcomes.
Types of medulloblastoma and prognosis
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)
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
Support for patients with medulloblastoma
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.
Late effects of medulloblastoma treatment
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.
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.
Questions to ask your child’s care team
What are our treatment options?
What are the possible side effects of each treatment?
What can be done to manage side effects?
Will my child need to be in the hospital for treatment?
Where is the treatment available? Is it close to home or will we have to travel?
Key points about medulloblastoma
Medulloblastoma is the most common malignant brain tumor in children. It begins in the cerebellum, an area in the back of the brain.
Medulloblastomas are fast-growing.
The overall survival rate for childhood medulloblastoma in the United States is 70–80% (7–8 of 10) if it has not spread.
Your child’s care team is the best source of information about your child’s case.
Treatment can include surgery, radiation, and chemotherapy.
Medulloblastoma survivors can have a variety of treatment-related problems.
Radiation therapy is a common cancer treatment for many types of pediatric cancers. Learn about radiation therapy and what to expect during radiation treatments.
Chemotherapy treats cancer using medicines that work by interfering with cells as they divide. Learn more about chemo and how to prepare your child for it.
