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Medulloblastoma in Children and Teens

What is medulloblastoma?

Medulloblastoma is the most common malignant brain tumor in children. It begins in the cerebellum, an area in the back of the brain.

Medulloblastoma is a brain tumor that begins in the cerebellum. The cerebellum is in a part of the brain called the posterior fossa.

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. 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:

  1. WNT subtype, pronounced “wint”
  2. SHH subtype, also known as Sonic hedgehog (SHH) medulloblastoma
  3. Group 3 medulloblastoma
  4. Group 4 medulloblastoma

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:

Medulloblastoma is divided into 4 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.

Medulloblastoma is divided into 4 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% if the disease has not spread. If the disease has spread, the survival rate is about 60%.

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 (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.

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:
MRI scan with markings showing medulloblastoma in the cerebellum.

MRI scan with markings showing medulloblastoma in the cerebellum.

Diagnosis of medulloblastoma

Doctors evaluate medulloblastoma in several ways.

  • Physical exam and health history 
  • Neurological exam 
  • Magnetic resonance imaging (MRI) 
  • 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.
  • Biopsy

Types of medulloblastoma

Medulloblastoma is classed or described based on disease risk and prognosis. To help plan treatments, the doctors look at:

  • Histology (studying tissues and cells under a microscope)
  • Molecular features (such as gene changes)
  • Metastasis (spread of cancer)

Histology

Histology looks at features such as size and shape of the tumor cells to class medulloblastoma tumors:

  • Classic medulloblastoma is made up of small, round cells. The cells are close together and have dark nuclei (the center of the cell where the cell’s information is stored).
  • Desmoplastic/nodular medulloblastoma appears as round nodules ringed by connective tissue with cells close together.
  • Medulloblastoma with extensive nodularity (MBEN) contains more round nodules.
  • Anaplastic medulloblastoma is made up of irregularly shaped cells.
  • Large cell medulloblastoma has tumor cells with large nuclei.

Anaplastic and large cells often appear together. They are grouped as large cell anaplastic (LCA) tumors.

Molecular features

Based on the tumor’s molecular features, medulloblastoma groups include:

  • WNT
  • SHH
  • Group 3
  • Group 4

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.

Metastasis

Medulloblastoma may also be classed by metastasis, or spread of disease:

  • M0: The tumor is localized with no spread of disease.
  • M1: Tumor cells are found in the brain fluid called cerebrospinal fluid (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.

Treatment of medulloblastoma

Medulloblastoma treatment includes:

Risk-based approaches to medulloblastoma treatment classify patients based on tumor features and predicted outcomes. Doctors consider:

  • Molecular subgroup of medulloblastoma
  • Whether surgery completely removed the tumor
  • Whether the tumor has spread
  • Tumor histology (what it looks like under the microscope)
  • Genetic features of the tumor

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

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. 

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 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.

Radiation therapy uses beams of radiation, X-rays or protons, to shrink tumors and kill cancer cells. Radiation works by damaging the DNA inside cancer cells.

Radiation therapy uses beams of radiation to shrink tumors and destroy cancer cells. Radiation works by damaging the DNA inside cancer cells.

Proton therapy uses protons as its energy source. In proton radiation the beam can stop at the tumor site. This allows doctors to aim high doses of radiation at tumors and minimize damage to nearby healthy cells.

Proton therapy uses protons as its energy source. In proton radiation the beam can stop at the tumor site. This allows doctors to aim high doses of radiation at tumors and reduce damage to nearby healthy cells.

Chemotherapy

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 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 could help treat your child’s disease.

Medulloblastoma in infants

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.

Medulloblastoma prognosis

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.

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 good 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)
• Desmoplastic / nodular
• MBEN
• Classic
• Large cell anaplastic
• Classic
• Large cell anaplastic
• Classic
• 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

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.

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. 

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% 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.


Reviewed: May 2023