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Medulloblastoma

Medulloblastoma is the second most common brain tumour in children. But it is the most common malignant (high grade) children’s brain tumour.

Around 55 children are diagnosed with medulloblastoma each year in the UK.

What is medulloblastoma?

Medulloblastoma develops at the back of the brain in the cerebellum.

Diagram showing the main parts of the brain

It is likely to grow quickly and can spread to other areas of the brain and spinal cord. Between 33 to 35 out of 100 children (33 - 35%) have medulloblastoma that has spread when they are first diagnosed.

Until recently, doctors talked about medulloblastoma as a PNET. PNET (pronounced pee-net) stands for primitive neuro ectodermal tumour. Research has now shown us that medulloblastoma cells are different from those in other PNET tumours. So, doctors now describe it as an embryonal tumour.

Because this change is quite new, you still might hear or read medulloblastoma being described as a PNET.

Medulloblastoma is most commonly diagnosed in children between 3 and 4 and between 8 and 10 years old. And it’s slightly more common in boys than girls.

Risks and causes

Most people worry about what caused their child to develop cancer. We don’t know what causes, or how to prevent most childhood cancers, including medulloblastoma.

We know that there is an increased risk of medulloblastoma with some inherited family cancer syndromes. But remember, not every child with one of these syndromes develops medulloblastoma. Around 5 out of every 100 cases of medulloblastoma (around 5%) are linked with either:

  • familial adenomatous polyposis (FAP) - sometimes known as Turcot syndrome
  • nevoid basal cell carcinoma syndrome (NBCCS) – also known as Gorlin syndrome

Signs and symptoms

Your child might have symptoms for a few weeks or months before they are diagnosed with medulloblastoma. Many of the symptoms are general and non specific. Some are similar to less serious childhood illnesses. Symptoms include:

  • headaches in the morning
  • feeling or being sick – being sick often makes the headaches feel better
  • double vision
  • finding it hard to sit or stand unsupported – your child might often fall backwards
  • being more fractious or irritable – it might be taking longer than usual to get your young child to settle
  • loss of appetite
  • behaviour changes – they might be interacting with you or their siblings less

A symptom that is sometimes found during a young infants routine development check up is an increasing head size (head circumference).  Or the soft spot on top of the skull (fontanelle) might be swollen. 

Take your child to your GP if you are worried your child has a symptom of a brain tumour.

Tests

The first tests your child might have are a:

  • CT scan
  • MRI scan

They might also have a lumbar puncture. This is a test to check for cancer cells in the fluid that surrounds the brain and the spine. This fluid is called cerebrospinal fluid (CSF). Your child’s doctor or specialist nurse will take a sample from the fluid around their spine.

For some types of test, your child might need sedation or a general anaesthetic, including a lumbar puncture. This is to help them lie still.

Getting diagnosed

We have information for parents whose child has just been diagnosed with cancer. It has information about what to expect.

Even if you have been told that a brain tumour is a possibility, hearing this confirmed by a doctor can be shocking. 

Types

Researchers are learning more about medulloblastoma all the time. At the moment, medulloblastoma is grouped by what the cells look like under the microscope. Your child’s doctors need a sample of the tumour to work out which type it is. This means they won’t be able to tell you straight away about what type or group it is. 

There are 4 groups:

  • classical medulloblastoma – around 8 out of 10 children (around 80%) have classical medulloblastoma
  • anaplastic or large cell medulloblastoma
  • nodular or desmoplastic medulloblastoma – this type is most common in infants
  • medulloblastoma with extensive nodularity (MBEN)
Talk with your child’s consultant about their type of medulloblastoma. And what this means for your child’s treatment plan.

Inside the cells

Using new techniques, scientists can also look at the genes and proteins inside the medulloblastoma cells. This means we can now group medulloblastoma into 4 further subtypes. These are:

  • subtype 1 – wingless (WNT) medulloblastoma
  • subtype 2 – sonic hedgehog (SHH) medulloblastoma
  • subtype 2 – group 3 medulloblastoma
  • subtype 4 – group 4 medulloblastoma

Researchers are interested in learning more about these differences in medulloblastoma. They hope to make treatments targeted to these gene changes in the future.

Watch a video to see how Cancer Research UK is funding research into these subtypes of medulloblastoma.

Treatment

The main treatments for medulloblastoma are:

  • surgery
  • radiotherapy
  • chemotherapy

Each child has their own treatment plan. Surgery is usually the first treatment your child will have. Less commonly your child might have chemotherapy first to shrink the tumour before surgery.

Your child’s specialist team decides on the best treatment for your child. Both you and your child will be involved in decisions about treatment and care. 

Surgery

Surgery is usually the first treatment your child will have. 

Your child has surgery to remove as much of the tumour as possible. At the same time, your child’s surgeon takes a piece of the tumour to look at under the microscope. This is to find out what type of medulloblastoma it is.

Hearing your child needs brain surgery can feel very frightening. A paediatric neurosurgeon does the operation. They are highly specialised and skilled professionals in looking after children with brain tumours. 

Fluid build up

Posterior fossa syndrome

25 to 30 out of 100 children (25-30%) have particular symptoms after surgery to the back of the brain. The symptoms are called posterior fossa syndrome. They can be very mild or severe. Symptoms include difficulty talking, swallowing or walking.

Posterior fossa syndrome might develop anytime from one day to a week after surgery. The symptoms usually improve slowly over a few weeks or months. But they may not go away completely in some people. Research is trying to find out what causes posterior fossa syndrome. 

Decisions about treatment (after surgery)

The treatment your child has after surgery depends on a number of factors. These include:

  • what the cells look like under the microscope – the type of medulloblastoma
  • if the medulloblastoma has spread
  • how old your child is

Based on these factors, your child goes into one of two treatment groups. These are based on the risk of medulloblastoma coming back after treatment. These groups are:

  • high risk
  • standard risk

High risk

Your child only needs one of these factors to be in the high risk group:

  • they are under 3 years old
  • they have medulloblastoma that has spread
  • their surgeon was not able to remove all of the tumour and the tumour that is left is more than 1.5cm in size
  • they have large cell or anaplastic medulloblastoma
  • they have certain gene changes

Standard risk

Every child in the standard risk group is 3 years or over. Their surgeon was able to remove all of their tumour, or they only have a very small amount left. Their medulloblastoma has not spread.

Treatment for children under 3

All patients under the age of 3 are in the high risk group.

Your child’s specialist will usually avoid using radiotherapy to the whole brain and spine if your child is younger than 3. This is to reduce the risk of them developing long term side effects which is higher in children younger than 3.

Chemotherapy

Chemotherapy is the use of anti cancer drugs to destroy cancer cells.

Your child’s specialist might recommend chemotherapy instead of whole brain and spine radiotherapy. This aims to keep your child's tumour under control until radiotherapy is likely to cause less damage.  

Medulloblastomas in very young children tend to be desmoplastic tumours. These tumours are very sensitive to treatment and can often be cured with chemotherapy on its own. Your child has high dose chemotherapy using a number of different drugs. They have these into their bloodstream, through a drip. They might also have chemotherapy into the fluid around the spinal cord (intrathecal chemotherapy). Drugs they might have include:

  • cisplatin
  • cyclophosphamide
  • vincristine
  • etoposide
  • methotrexate
  • procarbazine

Radiotherapy

Your child might also have radiotherapy just to the area containing the tumour. This way, radiotherapy to the whole brain and spinal cord can be delayed until your child is older. Or, it might be avoided altogether.

Treatment for children 3 years and over

The exact treatment plan depends on your child’s risk group if they are over 3 years old.

Generally, children over 3 years old have:

  • chemotherapy
  • radiotherapy to the brain and spine

Some children aged between 3 and 6 years have chemotherapy only without radiotherapy. Your child’s specialist doctor will go over the risks and benefits of this treatment with you, if this is an option for your child.

Chemotherapy

Chemotherapy is the use of anti cancer drugs to destroy cancer cells.

Your child might have chemotherapy during or after radiotherapy.

The chemotherapy drugs your child might have include:

  • cisplatin
  • lomustine
  • vincristine
  • cyclophosphamide
  • carboplatin

Radiotherapy

External radiotherapy destroys cancer cells using radiation aimed at a cancer from a machine. Radiotherapy machines are very big. They usually rotate around your child to give treatment. But they don’t touch your child at any point.

Your child needs to keep still for their radiotherapy. For some young children, this means they need a general anaesthetic to help them lie still. Each individual dose, or fraction, of radiotherapy is quick and painless.

Radiotherapy usually starts around 4 to 6 weeks after surgery. And your child might have radiotherapy for up to 7 weeks.

Children’s radiotherapy teams are used to treat children with brain tumours. A play specialist will help your child prepare and cope with radiotherapy.

It can be daunting for you so the team will make sure you know what to expect too. Ask them any questions you have.

Treatment for medulloblastoma that has not gone away with treatment or has come back

It can be more difficult to treat medulloblastoma that has not gone away with treatment. Or, medulloblastoma that has come back after treatment. 

Treatments include:

  • surgery
  • radiotherapy
  • chemotherapy – usually tablets or liquids taken by mouth
  • a targeted cancer drug

Your child’s specialist will talk with you about the possible treatments for your child. They will involve you in any decisions about their treatment and care. Ask them any questions you have. 

Side effects of treatment for medulloblastoma

The side effects of treatment are different for each child. Some side effects of chemotherapy and radiotherapy happen during treatment and stop once treatment finishes. Other side effects happen months or years after treatment. These are called late side effects or long term effects. They can be mild or more challenging. Not all children have challenging long term side effects.

To help them with any long term side effects a team of specialists will closely monitor your child after treatment finishes.

The possible side effects of treatment might lead to problems at school or with your child meeting their developmental milestones.

We have detailed information on follow up and late effects of children’s brain tumour treatment, what treatments can help and where to get support. The brain tumour late effects service will provide long term support for your child.

Clinical trials

Researchers are interested in finding new and kinder ways to treat medulloblastoma. And ways to reduce the side effects of treatment. Many children have their treatment for a brain tumour as part of a clinical trial.

Coping

We have information about where to get help and support to help you cope.

Last reviewed: 
13 Mar 2019
  • Incidence statistics from Cancer Research UK (CancerStats)

    Accessed July 2018

  • The 2016 World Health Organization Classification of Tumors of the Central Nervous System: a summary

    DN Louis and others

    Acta Neuropathologica, 2016

  • Medulloblastoma

    NE Millard and KC De Braganca

    Journal of Child Neurology, 2016

    Volume 31, Issue 12

  • BMJ Best Practice: Medulloblastoma

    May 2017

  • The whole-genome landscape of medulloblastoma subtypes

    PA Northcott and others

    Nature, 2017

    Volume 547

  • Cancer in children – clinical management (6th edition)

    MCG Stevens, HN Caron and A Biondi

    Oxford University Press, 2012

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