What Is Medulloblastoma?

Dr. Sayour and Dr. Petrosiute are both St. Baldrick’s Scholars. This blog was written by Dr. Petrosiute in May 2014 and updated in April 2020 by Dr. Sayour.

What is medulloblastoma?

Medulloblastoma is the most common malignant brain tumor in children. It originates in the back part of the brain called the cerebellum. In up to 1/3 of cases, it can spread to other parts of the brain and spinal cord. Most cases are diagnosed before age 10.

What are the signs and symptoms of medulloblastoma?

The tumor usually blocks normal fluid movement around the brain, resulting in a buildup of fluid and increased pressure in the skull. As a result, patients often experience:

• Headaches
• Vomiting (often in the morning)
• Sleepiness or lack of energy
• Changes in vision

The cerebellum regulates balance and coordination, so some patients have trouble walking or become clumsier.

How is medulloblastoma diagnosed?

The tumor is initially diagnosed with a CT scan or MRI of the brain. Doctors will then obtain a sample of the tumor through a biopsy procedure or surgery to remove the tumor. A pathologist will then look at the tumor sample under the microscope to determine if it’s medulloblastoma or another type of childhood cancer, or if it’s benign (non-cancerous).

What treatment options are available for children with medulloblastoma?

The first step in designing a treatment plan for a child with medulloblastoma is determining whether the tumor is in one place or if it has metastasized, or spread. If the tumor is in one place, the best results for cure begin by removing most or all of it by surgery. This is followed by chemotherapy and radiation treatments to the brain and spinal cord. For patients younger than 3, the long-term side effects of radiation are severe, so doctors usually try to avoid it and instead use stronger chemotherapy. If there’s evidence that the tumor has spread, surgery is still helpful as are radiation and chemotherapy, but metastatic disease is much harder to treat and generally has a poor prognosis.

How is research helping children with medulloblastoma?

Scientists have learned a great deal about medulloblastoma over the past decade. It was once thought to be the same disease, no matter the patient or what the cells looked like under the microscope. Now we know there are specific types of medulloblastoma that can be diagnosed by looking at the mutations or other genetic changes that are found inside the cancer cells. These discoveries have aided in more streamlined therapies for medulloblastoma, now defined by subgroups. Thanks to these discoveries, treatments have evolved to be subgroup specific as opposed to a “one size fits all” model. As part of this streamlined approach, investigators are now exploring more targeted therapeutic approaches outside of surgery, radiation and chemotherapy. These approaches include novel therapies including utilizing small molecule inhibitors and immune based treatments. Since cancer cells are notorious for evading the immune system, researchers are attempting to find ways to reset this process and unlock the immune system against cancer. This field of research is called immunotherapy. Looking to the future, a greater understanding of how medulloblastoma overcomes the immune system could provide new insights that may ultimately lead to the development of new therapies for medulloblastoma.

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Read more on the St. Baldrick’s blog:

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• 5 Ways to Work Your Bald Head
• Announcing the Class of 2020: St. Baldrick’s Fellows and Summer Fellows