Embryonal tumours

Embryonal tumours develop from cells that are left over from the early stages of our development. That is while we were still developing in our mother’s womb. These cells are called embryonic cells. Normally these cells are harmless. But sometimes they can become cancerous.

There are different types of embryonal tumours. The most common type is medulloblastoma which mainly affects children.

Until recently, doctors talked about embryonal tumours as primitive neuro ectodermal tumours (PNETs). But doctors are now able to look at the tumour cells in more detail. So, they now describe them as embryonal tumours.  

Embryonal tumours can start anywhere in the brain or the spinal cord. They are likely to grow quickly and can spread through the cerebrospinal fluid to other parts of the brain and the spinal cord (high grade tumour).

Types of embryonal tumours

There are different types of embryonal tumours. These include:

  • medulloblastomas, which develop in the cerebellum
  • embryonal tumour with multilayered rosettes (ETMRs), which usually start in the cerebrum
  • medulloepitheliomas, which can develop in the brain or the spinal cord
  • atypical teratoid/rhabdoid tumours, which usually start in the cerebellum
  • CNS neuroblastomas, which can develop in the nerve tissue of the cerebrum or the layers of tissue that cover the brain (meninges)
  • CNS ganglioneuroblastomas, which develop in the nerve tissue of the brain and spinal cord
Diagram showing some of the main parts of the brain

How common it is

Embryonal tumours are rare. Around 2 out of every 100 brain tumours (2%) diagnosed in England between 2006 and 2010 were embryonal tumours. They are more common in children than in adults.

What tests will I have?

You have tests to diagnose an embryonal tumour. Your doctor checks the size of the tumour and whether it has spread. This helps your doctor plan your treatment. The tests you might have include:

  • MRI scan or CT scan
  • a biopsy of the tumour
  • a test to take a sample of fluid that surrounds your brain and spinal cord (lumbar puncture)


Your treatment depends on the type of embryonal tumour you have and whether it has spread to other parts of the brain. The main treatments for embryonal tumours are:

  • surgery
  • radiotherapy
  • surgery


Surgery is usually the first treatment you have. A highly specialised doctor (neurosurgeon) removes as much of the tumour as possible. The exact type of surgery you have depends on where the tumour is.

But it isn’t always possible to completely remove the tumour during the operation. Especially if the tumour is growing around important nerves or blood vessels. You might have radiotherapy and chemotherapy after surgery if this happens.


You might have radiotherapy to the brain and sometimes the whole of the spinal cord. You usually have it after surgery. Radiotherapy uses high energy x-rays to destroy tumour cells. This reduces the risk of the embryonal tumour coming back.


You might have chemotherapy after surgery or with radiotherapy. Chemotherapy uses cytotoxic drugs to kill tumours cells. It helps to reduce the risk of the tumour coming back or spread to other parts of the brain.

Follow up

You have regular appointments with your doctor or nurse after treatment finishes. Your doctor examines you at each appointment. They ask how you are feeling, whether you have had any symptoms or side effects, and if you are worried about anything.

You also have MRI scans on some visits. You usually have an MRI scan every 6 months.

Coping with an embryonal tumour

Coping with a diagnosis of a brain tumour can be difficult, both practically and emotionally. It can be especially difficult when you have a rare tumour. Being well informed about the type of tumour you have, and its treatment can make it easier to cope.  

Research and clinical trials

Doctors are always trying to improve the diagnosis and treatment of brain tumours. As part of your treatment, your doctor might ask you to take part in a clinical trial. This might be to test a new treatment or look at different combinations of existing treatments.

Last reviewed: 
04 Sep 2019
  • Cancer: Principles & Practice of Oncology (10th edition)
    VT DeVita, TS Lawrence and SA Rosenberg
    Lippincott, Williams and Wilkins, 2015

  • The 2016 World Health Organization Classification of Tumors of the Central Nervous System: a summary
    D Louis and others
    Acta Neuropathologica, 2016. Vol 131, Issue 6, Pages 803-820

  • Incidence statistics from Cancer Research UK (Cancer Stats)
    Accessed February 2019

  • The incidence of medulloblastomas and primitive neuroectodermal tumour in adults and children
    N Smoll and K Drummond
    Journal of Clinical Neuroscience, 2012. Vol 19, Issue 11, Pages 1541-1544

  • Guidelines on the diagnosis and management of Adults PNETs
    British Neuro-Oncology Society, 2011

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. Please contact patientinformation@cancer.org.uk with details of the particular issue you are interested in if you need additional references for this information.

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