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 and am I at risk?
There are about 350 new cases of medulloblastoma diagnosed every year. Medulloblastoma makes up about 20% of all pediatric CNS cancers. About 75% of medulloblastoma cases occur in children under the age of 10; with 20% of these cases happening in infants under the age of 2. Boys have a slightly higher incidence of medulloblastoma than girls. It can also occur in adults, but this is very rare.
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.
How can medulloblastoma in a child be prevented?
Children with medulloblastoma usually do not have any risk factors. Because of this, there is no way to prevent it.
What screening tests are used?
There are no recommended screening tests for childhood cancer. A child won’t be tested for medulloblastoma unless they are showing signs or symptoms of the disease.
What are the signs and symptoms?
The most common symptom is frequent, severe vomiting (throwing up), especially in the morning. Other symptoms include:
- Headaches, which may be worse in the morning.
- Vision changes; like 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?
The best way to diagnose medulloblastoma is through MRI of the brain. This is usually given with contrast dye to enhance the images. Other tests in the diagnostic work-up may 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. Over the past 10 years, we have come to understand more and more about the genetic changes that can be part of medulloblastoma. Your child’s tumor will be tested for various genetic changes, and these may determine parts of the way that your child’s disease is treated. Your child’s treatment plan in terms of timing and which type(s) of treatment they receive may differ from another child’s plan.
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 care team about rehabilitation plans after your child’s brain surgery.
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:
- Radiation is first delivered to the entire CNS (brain and spine) at a lower dose. This is called CSI or craniospinal irradiation.
- 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.
There are many potential side effects of radiation in children; many of which can be long-term or occur many years after treatment. These side effects can include:
- Memory changes.
- Challenges with learning.
- Changes to hormone levels.
- Hearing problems.
- Slowed or delayed growth.
- Behavior/mood/social adjustment challenges.
The development of side effects is impacted by many factors, including the extent of the pre-radiation surgery, how much of the brain and where in the brain is to be treated, the age of the child, and the overall radiation dose. Because children under the age of 3 are much earlier in their development stages, some treatment teams may try not to use CSI. Chemotherapy is often used first or instead of CSI in younger children. Also, in these very young children, radiation is sometimes only given to a part of the brain, not the entire brain and spine.
As more precise methods of delivering radiation have been developed, there has been less risk of damage to surrounding tissues/organs including the inner ear and the memory section of the brain. This includes the use of IMRT (intensity-modulated radiation therapy) and proton therapy. These are more precise methods of radiation that can help lower the risk of radiation to parts of the brain near the original tumor site.
Even though the actual size of the CNS that is irradiated is small, a large amount of normal tissue is exposed to radiation with photon radiotherapy (traditional radiation therapy), including the heart, lung, bowel, testicles (males), ovaries (females), and bones in the spine. Proton radiotherapy offers a major potential advantage over photons for the radiation of the spinal.
Photons (which are used in traditional radiation) enter the body, reach the tumor and continue through the body, exiting on the opposite side. This exposes the tissues in front and behind the tumor to radiation. This treatment puts these tissues and organs at risk for damage. Proton therapy works differently; 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 virtually 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 helps to protect sensitive structures like the middle ear, reducing the risk of long term hearing loss. Proton therapy is available at select centers worldwide and is used for many children who require radiotherapy for medulloblastoma.
While no radiation therapy is without side effects, it can be planned and given in such a way as to minimize potential long-term side-effects. This is best done at a major radiation oncology center where there is a team of providers who are familiar with pediatric patients and technologically capable of treating childhood cancers.
Chemotherapy is also used to treat medulloblastoma. 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. Chemotherapy medications used in the treatment of medulloblastoma include cisplatin, vincristine, and CCNU. Chemotherapy is very important in the treatment of children under 3 who are at a higher risk for developmental side effects related to radiation.
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
Because the brain and spine are the targets of many treatments for medulloblastoma, patients can experience side effects impacting cognitive development (thoughts, behaviors, speech, mobility), vision, and hearing. These side effects can happen during and after treatment; sometimes many years after treatment. It is important to talk with your child’s care team about managing these side effects. Neuropsychologists can be very helpful when assessing cognitive changes due to treatment and can work with your child’s school to meet their developmental and educational needs. You may also want to talk with your child’s team about the potential impact of treatment on their fertility (ability to have a child).
After treatment for childhood cancer, you will be followed closely to monitor for the cancer coming back, to manage ongoing side effects, and to transition to survivorship. At first, you will have frequent appointments with providers and have ongoing tests to monitor your health and possible recurrence of your cancer. As time goes on, these visits and testing will become less frequent. The oncology team will discuss the plan for follow up.
What can you do to live a healthy life after treatment? There is no supplement or specific food you can eat to assure good health, but there are things you can do to live healthier, prevent other diseases, detect cancers early and work with the social and emotional issues, including insurance, employment, relationships, sexual functioning, and fertility, that a prior cancer diagnosis sometimes brings with it. Your oncology team is there to support you and can help you find support resources.
It is important to have a plan for who will provide follow up care (an oncologist, survivorship doctor or primary care doctor). Talk with the team about developing 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 survivor's 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.
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