Medulloblastoma is a brain tumor predominantly affecting children. It is aggressive and challenging to treat, but outcomes are often optimistic.

Medulloblastoma is a central nervous system tumor. It originates in the cerebellum, which is at the lower back part of the brain. The cerebellum is crucial for motor control.

The challenge with medulloblastoma lies in its aggressive growth and potential to metastasize, or spread, to the spinal cord.

Although it can occur at any age, it is more common in children and males. Around 4,000 people live with medulloblastomas in the United States.

While treatment typically involves surgery, radiation, and chemotherapy, these interventions carry significant risks, especially for children whose brains and bodies are still developing.

This article explores medulloblastoma, its symptoms, diagnosis, and outlook.

a close up photo of a young child's fingers pointing at text in a bookShare on Pinterest
Gary John Norman/Getty Images

Medulloblastoma is a type of brain cancer that predominantly affects children. It comprises about 1 in 5 of all pediatric brain tumors, making it the most common cancerous brain tumor in this age group.

Experts classify medulloblastoma as an embryonal neuroepithelial tumor originating from the embryonic cells in the cerebellum. This region is responsible for coordinating movement and balance.

These cancers tend to grow rapidly and can spread aggressively through the cerebrospinal fluid (CSF). Doctors find the diagnosis and treatment of medulloblastoma complex due to its aggressive nature and the sensitive location within the brain.

Experts recognize four medulloblastoma subtypes, each defined by unique behaviors and characteristics. The subtype can also influence the treatment approach and outlook.

According to the nonprofit Brain Tumor Research, the subtypes are:

WNT-activated medulloblastoma

This is the most common subtype. It arises from the WNT signaling pathway, a chain of molecular interactions essential for cell growth. Dysregulation in this pathway can lead to tumor development.

Sonic hedgehog (SHH)-activated medulloblastoma

Named after the “Sonic the Hedgehog” protein, this subtype involves overactivity in the SHH pathway, which is crucial for embryonic development. An imbalance can result in the excessive growth of brain cells, leading to tumor formation.

It is commonly seen in adults and children under 3 years old.

Group 3 medulloblastoma

This subtype is recognized for its aggressiveness and tendency to spread to the brain’s ventricles and spinal cord.

It often involves amplifying the MYC gene. This can signal a poorer outlook, especially in children. Researchers are exploring the role of the NOTCH1 protein in the progression of these tumors.

Group 4 medulloblastoma

This is the most prominent subtype, representing about one-third of cases.

The genetic and molecular characteristics of group 4 medulloblastoma are generally less understood than other types.

People with medulloblastoma may experience walking, balance, and fine motor issues. Children may have behavioral or learning difficulties.

If the tumor blocks CSF, it can lead to hydrocephalus or increased pressure inside the skull. Symptoms of hydrocephalus include:

  • nausea and vomiting
  • sleepiness
  • vision issues
  • headaches
  • confusion
  • seizures
  • fainting

If medulloblastoma spreads to the spine, a person may experience:

The causes of medulloblastoma are not entirely clear.

However, many cases involve gene mutations that affect brain development and function. Some of these genetic changes occur spontaneously. Others are part of inherited syndromes that predispose people to cancer.

For instance, mutations in the CTNNB1 gene are involved in the WNT subtype of medulloblastoma. These changes affect the beta-catenin protein, which is crucial for cell growth and division.

Alterations in other genes, such as PTCH1, can lead to conditions such as Gorlin syndrome, which increases the risk of developing medulloblastoma.

Environmental factors may also play a role. These may include:

  • maternal diet
  • blood disorders during pregnancy
  • viral infections, such as the John Cunningham (JC) virus or human cytomegalovirus (CMV) in early childhood

Additionally, medulloblastoma can have a familial association and can occur alongside other syndromes, including:

Diagnosis typically involves imaging tests, such as CT or MRI scans of the brain, followed by a biopsy to confirm the presence of cancerous cells.

Doctors may also use a lumbar puncture and perform a CSF analysis. It may show whether cancer cells have spread.

The tumor’s classification — which can influence the treatment approach — is based on molecular and genetic analysis. There are five histological subtypes:

  • classic
  • desmoplastic
  • anaplastic
  • large cell
  • medulloblastoma with extensive nodularity (MBEN)

The classic subtype is the most common. Desmoplastic and MBEN subtypes tend to have the best outcomes.

Treatment for medulloblastoma usually involves surgery and radiation therapy.

Surgical removal of as much of the tumor as possible is the first step. Radiation therapy usually follows surgery and targets any remaining cancer cells.

Doctors may also use chemotherapy as part of the treatment plan.

Recent developments in molecularly targeted therapies may offer more personalized treatment options based on the tumor’s genetic makeup. A person can consult a cancer specialist called an oncologist to learn more about these options.

If possible, working with a pediatric oncologist in a pediatric cancer center is the best option for children with medulloblastoma.

Learn more about targeted cancer therapy.

The survival rates for medulloblastoma have improved significantly with advances in treatment.

The 5-year survival rate for people with an average-risk tumor is 85%. It is 40% or less for people with high risk tumors. In children under age 3 years, survival rates vary from 30–70%.

Some factors affecting a person’s outlook may include:

  • age
  • tumor subtype
  • extent of tumor spread
  • treatment response

Medulloblastoma is a complex brain cancer originating in the cerebellum. It primarily affects children but can occur at any age.

Its exact causes are not fully understood, but genetic factors play a significant role.

The diagnostic process typically involves advanced imaging tests and a tissue biopsy to confirm the presence and type of the tumor.

Treatment strategies are comprehensive and involve surgical resection, radiation therapy, and chemotherapy. Some factors, including the tumor’s molecular subtype and the person’s age, can help a doctor tailor treatment.

Over recent years, improvements in treatment approaches have significantly improved survival rates, particularly for children.