All About Medulloblastoma

What is medulloblastoma?

Medulloblastoma is a type of brain tumor. Medulloblastomas are tumors in the cerebellum section of the brain. The cerebellum is located in the back part of the brain and controls things like walking, eye movements, balance, muscle coordination, and speech. Medulloblastoma can spread to other parts of the central nervous system (CNS) through the cerebrospinal fluid (CSF).

What causes medulloblastoma?

The exact cause of medulloblastoma is not known. It does not seem to “run in families.” However, there is a higher risk of medulloblastoma with some genetic syndromes, such as Gorlin’s syndrome and Turcot’s syndrome.

What are the symptoms of medulloblastoma?

The symptoms of medulloblastoma can be: 

• Headaches, which may be worse in the morning.
• Nausea.
• Vision changes, such as double vision.
• Unsteadiness/clumsiness when walking.
• Changes in mood, behavior, or personality.
• Loss of balance.
• Loss of appetite.
• Fatigue and sleepiness.

How is medulloblastoma diagnosed?

If your child is showing symptoms of medulloblastoma, they will have an MRI of their brain. This is usually done with contrast dye so that the images are easier to see. Other tests might include an MRI of the spine and a lumbar puncture (LP) to check for spread of the disease to the spine. During an LP, a thin needle is inserted into the lower back and a sample of cerebrospinal fluid (CSF) is removed. The cells are then looked at under a microscope to confirm the diagnosis.

How is medulloblastoma treated?

Medulloblastoma is usually treated with a combination of treatments including surgery, radiation, and chemotherapy. Your child’s tumor will be tested for genetic changes. This can help figure out treatment options. The timing and which type(s) of treatment your child may receive may be different from another child’s plan.

Surgery

The goal of surgery for medulloblastoma is to remove as much of the tumor while sparing as much of the surrounding healthy brain tissue. While this is the goal for all patients with medulloblastoma, it is not always possible. Sometimes the tumor has grown into other parts of the brain, making it difficult to remove it all without risking serious side effects/brain injury.

Any surgery comes with risks. One known risk after brain surgery involving the cerebellum is posterior fossa syndrome. This syndrome can cause many side effects after surgery, including:

• Difficulty swallowing.
• Balance problems.
• Inability to speak.
• Decreased muscle tone.
• Changes in mood and behavior.

These side effects can last for months but do usually get better slowly. Be sure to talk with your child's care team about rehabilitation plans after your child’s brain surgery.

Radiation

After surgery, radiation is used to prevent the tumor from coming back. Even if the surgery removes all of the tumor and there has been no spread to the spine or other parts of the brain, radiation is used to prevent a recurrence.

Radiation for medulloblastoma is usually given in two steps:

1. Radiation is first given to the entire CNS (brain and spine) at a lower dose. This is called craniospinal irradiation (CSI).
2. Radiation is then given to just the area where the original tumor was located in the brain. This is given at a higher dose and is sometimes called a “tumor bed boost.” This second step helps to treat any cancer cells that may have been left behind or too small to see on MRI.

Side effects of radiation can be long-term or can happen many years after treatment. The side effects can include:

• Memory changes.
• Challenges with learning.
• Changes to hormone levels.
• Hearing problems.
• Slowed or delayed growth.
• Behavior/mood/social adjustment challenges.

Whether your child develops side effects depends on things like:

• The extent of pre-radiation surgery.
• Your child’s age.
• The overall amount of radiation your child is getting.
• The area of the brain being treated.
• How much of the brain is being treated.

 Since children under 3 years old are much earlier in developmental stages, chemotherapy might be used first or instead of CSI. In some cases, for children under 3, radiation might be given to a part of the brain, not the entire brain and spine.

IMRT (intensity-modulated radiation therapy) and proton therapy are precise treatments. This means they can help lower the risk of radiation to parts of the brain near the original tumor site. Precise treatments lessen the risk of damage to areas like the inner ear and memory section of the brain.  

Proton Therapy

Proton therapy is a type of external-beam radiation therapy used to treat cancer. It uses protons, rather than the X-rays used in conventional (photon) radiation therapy. Proton radiotherapy is often used when radiation is being given to the spine because it limits large amounts of tissue being exposed to radiation.

Proton therapy works by entering the body and reaching its peak dose at the tumor and stopping, exposing tissues in front of the tumor to lower doses of radiation and tissues behind the tumor to no radiation. As a result, there is an improvement in the delivery of radiation to the target (the tumor) while there is less or no damage to normal tissues behind the tumor. This can reduce the side effects. Proton therapy is also used in the “tumor bed boost” step of radiation therapy. This means that radiation is given in a higher dose just to where the original tumor was located. This helps to protect areas like the middle ear, reducing the risk of long-term hearing loss. Radiation therapy can have side effects, but it can be planned and given in a way that minimizes potential long-term side effects. Proton therapy is available at select centers worldwide and is used for many children who require radiotherapy for medulloblastoma.

Chemotherapy

Chemotherapy is the use of medications to kill cancer cells. Chemotherapy can be given in a number of ways, including into a vein (IV), by mouth, into a muscle, or into the cerebrospinal fluid. When treating medulloblastoma, chemotherapy is given after surgery, the medications used might include:

• Cisplatin (Platinol®).
• Cyclophosphamide - IV (Cytoxan®, Neosar®, Endoxan®).
• Vincristine (Oncovin®, Vincasar PFS®, VCR).
• Lomustine (CeeNU®, CCNU, Gleostine™).
• Etoposide (Toposar®, VePesid®, Etopophos®,VP-16).
• Methotrexate (Mexate®, Folex®, Rheumatrex®, Amethopterin, MTX).

Children under 3 years old are at a higher risk for developmental side effects related to radiation, so they are often treated with chemotherapy.

Clinical Trials

There are clinical research trials for most types of cancer and every stage of the disease. Clinical trials are designed to determine the value of specific treatments. Trials are often designed to treat a certain stage of cancer, either as the first form of treatment offered or as an option for treatment after other treatments have failed to work. They can be used to evaluate medications or treatments to prevent cancer, detect it earlier, or help manage side effects. Clinical trials are extremely important in furthering our knowledge of disease. It is through clinical trials that we know what we do today, and many exciting new therapies are currently being tested. Talk to your provider about participating in clinical trials in your area. You can also explore currently open clinical trials using the OncoLink Clinical Trials Matching Service.

Follow-Up Care & Survivorship

The brain and spine are the targets for many treatments for medulloblastoma. This can cause side effects that impact cognitive development (thoughts, behaviors, speech, mobility), vision, and hearing. These side effects can happen during and after treatment; sometimes many years after treatment. A neuropsychologist can help assess cognitive changes due to treatment and can work with your child’s school to meet their developmental and educational needs. You might want to talk to your child’s provider about the impact treatment can have on their fertility (ability to have a child).

You, your child, their caregivers, and providers will work together to talk about the best treatment options for your child. Be sure to ask your child’s provider about potential late or long-term side effects (side effects that can happen after treatment has ended). Talk with your child’s provider about making a survivorship care plan or develop one using the Smart ALACC tool. Your child may benefit from being seen in a survivorship clinic. At a survivorship clinic, a provider can review your child's history and provide recommendations. You can contact cancer centers in your area to see if they have a survivorship clinic or search for a clinic on OncoLink's survivorship clinic list.

Resources for More Information

Medulloblastoma Resource Network

Provides information and education about medulloblastoma and its treatment.

https://medulloblastoma.org/