Medulloblastoma

Medulloblastoma is the most common malignant or high-grade paediatric brain tumour.

At least 75% of medulloblastomas occur in the cerebellum at the back and base of the brain.

Medulloblastoma brain cancer is usually diagnosed as a grade 3 or grade 4 tumour. It is more common in boys than girls and is rarer in adults. It originates in embryonic (foetal) tissue hence is classified as an embryonal tumour, and is typically discovered during the first five years of life.

The causes of a medulloblastoma are not yet clear, although SHH-activated medulloblastomas can sometimes be associated with a pre-existing condition called Gorlin Syndrome, also known as nevoid basal cell carcinoma syndrome. Gorlin Syndrome can lead to various types of cancer, including basal cell carcinoma, the most common form of skin cancer.

Find out more about causes of brain tumours

What are the symptoms of medulloblastoma?

Medulloblastoma often occurs in the cerebellum, the area governing motor functions such as movement, balance and co-ordination.

Symptoms resulting from medulloblastoma growth can include:

Problems with walking
Increased stumbling and falling
General co-ordination issues, with increasing clumsiness for example

When a tumour in the cerebellum grows, it can interfere with the circulation of fluid between the spinal column and the brain which can lead to a build-up of pressure inside the head.

This can give rise to additional symptoms such as:

Headaches that tend to be worse after lying down for a while (for example, on waking up in the morning)
Generally feeling tired or unwell
Failure to feed properly
Feeling sick or actually vomiting
Abnormal eye movements
Blurry vision caused by swelling at the back of the eye

If the tumour spreads down into the spinal cord, it can cause other symptoms such as:

Back pain that gets worse after resting or sleeping
Problems with walking
Trouble controlling bowel or bladder function

What are the different types of medulloblastoma and what do they mean?

Medulloblastomas are classified into four main groups using molecular and genetic analysis of biopsy tissue, and then into further subgroups using histology – variations identified on examination of tumour cells under a microscope. Tumours are thus given detailed, integrated classifications that are used to indicate a potential prognosis and guide treatment.

The size, shape and physical characteristics of tumour cells when viewed through a microscope are reflected in names such as ‘large cell’ or ‘nodular’ medulloblastoma, but the four main groups of this tumour type are defined by how they act rather than how they look.

WNT-activated medulloblastoma
WNT-activated medulloblastoma is the most common form of medulloblastoma. It is named after the WNT pathway, a specific series of molecules which influence each other, and is a process that can in turn affect tumour growth.
Sonic Hedgehog (SHH) activated medulloblastoma
The SHH pathway also affects tumour growth (named after the video game character “Sonic the Hedgehog” by the scientists who discovered it). When messages are passed along molecules in the SHH pathway in a balanced way, it helps to control healthy embryonic development. Excessive SHH activity means that the body doesn’t stop producing this type of brain cell when it otherwise would do, so a tumour can then form from this build-up of cells.

Sonic Hedgehog pathway activation is a commonly associated with medulloblastoma in adults (patients aged 16 years or over), as well as those occurring in children under three years old.
Group 3 medulloblastoma
This is the most aggressive form of medulloblastoma and tends to spread through the ventricles of the brain and into the spinal cord. This type of tumour usually has extra copies of the MYC gene, referred to as MYC amplification.

Tumours will be tested for this as it is the most important indicator of a shortened prognosis in paediatric medulloblastoma. This is rare in adult medulloblastomas.

There is also a cell signalling pathway controlled by a protein called NOTCH1 that scientists believe is influencing the aggressive nature of these Group 3 tumours. Ongoing research projects and clinical trials are trying to identify effective drugs that could block the action of NOTCH1.
Group 4 medulloblastoma
The largest subtype, Group 4 medulloblastoma accounts for up to 30% of patients diagnosed with this tumour type. However, the molecular make-up of these tumours is the least well understood.

What treatments are used for medulloblastoma?

Surgery to remove all or as much of the tumour as possible usually comes first. This may include the insertion of a shunt in order to divert or regulate the flow of cerebral spinal fluid and/or a biopsy to extract some brain tumour tissue for classification and prognosis.

Surgery is likely to be followed by radiotherapy and chemotherapy.

Find our more about brain tumour treatments

What is the prognosis for a medulloblastoma?

Medulloblastoma can be treated with a combination of surgery, radiotherapy, and chemotherapy.

The likelihood of a complete cure depends on various factors, such as the age and overall health of the patient, the size and location of the tumour, and whether cancer has spread to other parts of the body. With modern treatment methods, the cure rate for medulloblastoma can be as high as 70-80% for children and 50-60% for adults. However, some patients may experience a recurrence of the tumour, which may require further treatment. Early diagnosis and prompt treatment can improve the chances of a successful outcome.

What is the survival rate for medulloblastoma?

Survival rates in children with medulloblastoma depend on the patient's age and if the tumour has spread. If the disease has not spread, survival rates are above 60%, but if it has spread to the spinal cord, the survival rate is reduced.

The exact type of medulloblastoma makes a difference to the prognosis. For example, a WNT-activated medulloblastoma is considered relatively low-risk with a better prognosis than those classified as Sonic Hedgehog (SHH) activated, grade 3 or grade 4.

For children and adults with a recurrent medulloblastoma (where the tumour grows back quickly despite having treatment to remove it), the prognosis is shorter, with a five-year survival rate of less than 40%.

Advances in surgery, radiation, and chemotherapy are contributing to an increase in survival rates, but side effects of treatment can produce long-term challenges for patients, including cognitive difficulties along with psychological and social problems. Longer term support services may be required in order to maximise quality of life.

Frequently asked questions

Is medulloblastoma malignant?

Yes, medulloblastoma is considered a malignant brain tumour. It is a type of cancer that arises in the cerebellum, which is the part of the brain responsible for coordination and balance. Medulloblastomas primarily affect children, although they can occur in adults as well.

Malignant tumours are characterized by the uncontrolled growth and spread of abnormal cells, and they have the potential to invade surrounding tissues and metastasize to other parts of the body. Treatment typically involves a combination of surgery, radiation therapy, and chemotherapy. The prognosis for medulloblastoma can vary depending on factors such as the age of the patient, the extent of the tumour, and the presence of certain genetic factors.

Is medulloblastoma cancer terminal?

Medulloblastoma can be life-threatening if left untreated or if cancer spreads to other parts of the body.

However, with prompt diagnosis and appropriate treatment, many patients with medulloblastoma can achieve long-term survival and even be cured of the disease. The likelihood of a complete cure depends on various factors, such as the age and overall health of the patient, the size and location of the tumour, and whether cancer has spread to other parts of the body. While some cases of medulloblastoma may be more difficult to treat than others, it is not necessarily considered terminal cancer.

What is the life expectancy with medulloblastoma?

The life expectancy for medulloblastoma varies. In children, outcomes have improved with advances in treatments, and many achieve long-term survival. Survival rates are less favourable in adults. Individual prognosis depends on factors like tumour characteristics and overall health. Consultation with medical professionals for personalized information is crucial.

How can we find a cure for medulloblastoma?

Research we are funding across all of our Centres of Excellence will help lead towards finding a cure for a wide range of brain tumours.

Pioneering researchers at our Brain Tumour Research Centre of Excellence at Queen Mary University of London are learning more about the molecular and genetic make-up of these challenging tumours in order to identify new ways to treat them. The team are also focused on using glioblastoma stem cells to help develop unique, patient-specific treatments that could translate across more than one type of brain tumour.

Our team at the University of Plymouth Brain Tumour Centre of Excellence are researching a number of molecular pathways that influence immune system function, tumour metabolism and tumour growth in a range of low-grade brain tumours. It is hoped that their findings will translate into other tumour types in the future.

The team of research and clinical experts at our Centre of Excellence at Imperial College, London, are working collaboratively with other research institutions to investigate the effectiveness of arginine-depleting drugs in the treatment of high-grade glioma brain tumours. They are also studying the way in which the ketogenic diet works in brain cancer. It is hoped that their findings may translate into other tumour types in the future

We also fund BRAIN UK at Southampton University, the UK’s only national tissue bank registry providing crucial access to brain tumour samples for researchers from all clinical neuroscience centres in the UK, effectively covering about 90% of the UK population, and an essential component in the fight to find a cure for medulloblastoma brain tumours.