What is Medulloblastoma?
Medulloblastoma is an embryonal tumour that develops at the base of the brain in a structure called the cerebellum. Although it begins in the cerebellum, tumour cells can spread through the cerebrospinal fluid (CSF) to other areas of the brain and spinal cord.
Medulloblastoma is considered a fast-growing tumour that requires prompt, specialised treatment, usually involving surgery, radiotherapy, and chemotherapy.
Who does Medulloblastoma affect?
Medulloblastoma is the most common malignant brain tumour in children and most often occurs during the first decade of life, although it can occasionally be diagnosed in older adolescents or adults.
Paediatric and adult medulloblastomas differ in their biological behaviour and genetic profile, reflecting distinct molecular subgroups and treatment considerations. Medulloblastoma occurs slightly more often in males than females, suggesting an underlying biological influence in tumour development.
Most cases arise sporadically, and doctors often cannot identify a clear cause. However, a small proportion of cases occur in association with inherited genetic syndromes. These include Li-Fraumeni syndrome (TP53 mutations), Gorlin syndrome (linked to the SHH pathway), and APC-associated polyposis syndromes such as Turcot syndrome, all of which can increase the risk of developing medulloblastoma.
Types and subgroups of medulloblastoma
Medulloblastoma is not a single disease, and doctors now tailor treatment according to the genetic and molecular features of the tumour. Because of variations across different molecular subtypes, treatment outcomes differ significantly. Some subtypes respond well to therapy, while others behave more aggressively.
WHO Classification of CNS Tumours divides medulloblastoma into four molecular subgroups: WNT-activated, SHH-activated (with TP53-wild type or TP53-mutant forms), and non-WNT/non-SHH, which include what were previously known as Group 3 and Group 4.
WNT-activated tumours carry a particularly favourable prognosis. Because of this, oncologists are actively exploring ways to safely reduce radiation exposure while maintaining excellent survival outcomes.
Certain non-WNT/non-SHH tumours, especially those previously classified as Group 3, tend to have a poorer prognosis. These tumours often show amplification of the MYC gene, which is associated with a higher risk of tumour spread and poorer treatment outcomes.
Doctors use this molecular classification to guide risk stratification and help determine how intensive treatment should be. Subtypes associated with better outcomes fall into lower-risk categories, while more aggressive subtypes fall into higher-risk categories. This approach allows the healthcare team to personalise treatment intensity.
Medulloblastoma is thought to arise from different precursor cells within the cerebellum, which contributes further to the biological diversity seen between subtypes.
Medulloblastoma Risk Groups
The prognosis for medulloblastoma depends on several factors, including the patient’s age at diagnosis, the molecular subtype of the tumour, whether the tumour has spread through cerebrospinal fluid, how much of the tumour can be removed during surgery, and the presence of certain genetic features (such as MYC or MYCN amplification) which are associated with poorer outcomes.
Based on these factors, medulloblastoma is often divided into risk groups that help guide treatment:
Survival rates can exceed 90% in some groups. This most clearly applies to WNT-activated tumours and select non-metastatic Group 4 tumours. Patients in this group may qualify for less aggressive treatment.
Survival rates are generally high, often around 75–90%, depending on subtype and treatment.
Survival rates are lower, often around 50–75% depending on subtype and spread. This group may include metastatic tumours or certain SHH and Group 4 tumours with higher-risk features.
Survival rates are often below 50%. This group can include Group 3 tumours with MYC amplification and metastases, as well as SHH tumours with TP53 mutations.
Your healthcare team will use these risk factors to recommend a treatment plan tailored to your tumour, balancing treatment effectiveness with long-term side effects.
Medulloblastoma Symptoms
Most people, predominantly children, with medulloblastoma initially experience symptoms such as headaches, nausea, vomiting (especially in the morning), or fatigue. These symptoms are often related to hydrocephalus, where the tumour blocks normal cerebrospinal fluid flow and increases pressure inside the brain, although some symptoms can also result from the tumour pressing on nearby structures.
As the tumour grows, symptoms related to the functions controlled by the cerebellum, including:
- Ataxia (problems with balance and coordination)
- Difficulty with writing or other fine motor tasks
- Vision problems, double vision or crossed eyes
If medulloblastoma spreads to the spinal cord through the cerebrospinal fluid, additional symptoms may appear, such as:
- Back pain
- Trouble walking
- Bowel changes
- Rarely, loss of bladder control
Because medulloblastoma can grow and spread quickly, symptoms may worsen over a short period of time. Your healthcare team may recommend immediate diagnostic testing, and it is important to contact them urgently if you notice a sudden increase or worsening of symptoms.
How Is Medulloblastoma Diagnosed?
A formal diagnosis for medulloblastoma involves several steps that help your healthcare team confirm the tumour type and plan the most effective treatment. It usually begins with an MRI of the brain, followed by MRI of the spine to check whether the tumour has spread through the cerebrospinal fluid (CSF), indicating metastatic dissemination.
Alongside imaging, your healthcare team will consider your clinical symptoms and may recommend CSF cytology, usually performed after surgery once it is safe to do so. Finding tumour cells in the CSF confirms that the disease has spread beyond the original location within the brain.
Tumour tissue obtained during surgery is then analysed using histological and molecular testing, guided by the imaging findings. These tests help confirm the molecular subgroup of medulloblastoma , which is crucial for tailoring treatment.
Based on these findings, your healthcare team will usually recommend surgery to remove as much of the tumour as safely possible. Further treatment often includes craniospinal radiotherapy and chemotherapy, particularly for higher-risk or metastatic tumours.
Although medulloblastoma is one tumour type, integrating imaging, histology, and molecular information allows clinicians to make a precise diagnosis and tailor treatment to each patient.
Medulloblastoma Treatment Options
Treatment for medulloblastoma usually begins with surgery to remove as much of the tumour as safely as possible. Surgery or a temporary drainage procedure may also be performed to relieve hydrocephalus, a condition where the growing tumour blocks the normal flow of cerebrospinal fluid and increases pressure within the brain.
During surgery, tumour tissue is collected for molecular testing to determine the specific medulloblastoma subgroup. This information (along with the amount of tumour remaining after surgery and whether the tumour has spread through the cerebrospinal fluid to the brain or spinal cord) helps your healthcare team decide the next steps in treatment.
Because medulloblastoma can spread through the CSF, your team may recommend craniospinal radiotherapy (CSI), which treats the entire brain and spinal cord. Radiation is usually delivered in small daily doses (fractions), followed by a higher focused dose at the tumour site to reduce the risk of recurrence. In very young children, especially those under 3 years, radiation may be delayed or avoided because of the risk of long-term effects on the developing brain. In these cases, chemotherapy is often used to delay or reduce the need for radiotherapy.
Depending on the tumour’s risk group and molecular subgroup, chemotherapy is usually given alongside radiation or after its completion to improve tumour control and reduce the risk of recurrence.
Side effects and long-term impacts
Medulloblastoma treatment can cause both short-term and long-term side effects, particularly because therapy often involves surgery, radiotherapy, and chemotherapy.
Short-term side effects may include nausea, fatigue, weight loss, diarrhoea, and changes in blood counts (hematologic toxicity). Most of these effects improve once treatment is completed, although some may take time to resolve.
Long-term effects can occur months or years after treatment. Children are particularly vulnerable to neurocognitive changes, such as difficulty learning new skills, slower processing speed, memory challenges, or reduced intellectual functioning. Treatments may also affect the endocrine system, especially if surgery or radiation impacts the pituitary gland or hypothalamic-pituitary region. This can lead to:
- Growth problems due to reduced growth hormone production
- Fertility issues caused by effects on sex hormone production or gonadal function
It is important to report any new symptoms or changes to your healthcare team immediately. Your team will usually develop a long-term follow-up plan to monitor your health and support you throughout life after medulloblastoma treatment.
Medulloblastoma Prognosis and Outlook
Medulloblastoma survival can vary depending on the tumour’s molecular subgroup and risk features. Current standard treatments have improved overall survival to around 70–80% for many children but outcomes differ among subgroups and risk groups.
WNT medulloblastoma has an excellent survival rate and a low risk of spreading through CSF. Current clinical trials are testing reduced radiation doses for some WNT patients to minimize long-term side effects while maintaining survival
Some Group 3 tumours with Myc amplification and SHH tumours with TP53 mutations have a poorer prognosis and are considered high-risk. Patients in higher risk groups usually receive more aggressive treatment, including surgery, craniospinal radiotherapy (CSI), and combination chemotherapy.
This risk-based approach helps your healthcare team tailor treatment intensity to maximize effectiveness while reducing the risk of long-term side effects where possible.
Research, Clinical Trials, and Hope for the Future
Current treatments for medulloblastoma can lead to significant neurocognitive, neuroendocrine, and psychosocial side effects; amplifying the need for clinicians and researchers to develop safer, more effective therapies.
Liquid biopsies (a doctor taking serial samples of CSF or blood) are being explored as a less invasive way to monitor treatment response. By detecting tumour DNA or biomarkers in these fluids, researchers hope to identify early signs of relapse and improve monitoring in the future.
Precision medicine offers another strategy to reduce treatment-related toxicity. Drugs that target specific genetic changes in the tumour may allow future treatments to use lower doses of conventional therapies. This may lead to lesser side effects later in life.
- Vismodegib targets SHH-subtype medulloblastoma and researchers are studying combinations with other drugs to improve its effectiveness.
- Drugs such as palbociclib, which affect how tumour cells repair DNA damage, have shown promising results in laboratory and early preclinical studies when combined with radiation.
- Adavosertib (AZD1775) may make tumour cells more sensitive to chemotherapy and radiation, and is being studied in clinical trials.
Immunotherapy is also being explored as a treatment option, which has so far shown more consistent benefit in adult cancers than in paediatric brain tumours. Early clinical trials using GD2-targeted CAR T cells have shown encouraging safety results and early signs of activity in some patients with GD2-positive medulloblastoma.
These advances reflect the ongoing effort to personalise treatment, reduce long-term toxicity, and improve outcomes for patients living with medulloblastoma.
Support for families and carers
When dealing with a medulloblastoma diagnosis, parents, carers and siblings often find themselves navigating complex medical decisions.
Support may include help understanding treatment options, coordinating care, managing practical challenges, and finding emotional support for the months ahead. Many families also need guidance in accessing second opinions, clinical trials, or palliative care services — and in knowing when to ask for help.
You do not have to manage this alone. Connecting with experienced support services like the National Advocacy Service can help connect you with information, resources and support tailored to your situation.
Visit our Support Hub for more information.
Disclaimer: All Cure Brain Cancer Foundation website content is created and published online for informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. You should seek your own medical advice from your doctor or other qualified health professionals.
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