Embryonal tumours

Embryonal tumours are brain tumours. They 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 brain 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
  • atypical teratoid/rhabdoid tumours, which usually start in the cerebellum
  • CNS neuroblastomas, fox 2 activated, which can develop in the nerve tissue of the cerebrum
  • CNS tumours with BCOR internal tandem duplication, which can develop anywhere in the brain or spinal cord
  • CNS embryonal tumours NEC/NOS - these are embryonal tumours that, for various reasons, can't be put into one of the other groups
Diagram showing some of the main parts of the brain

How common it is

Embryonal tumours are rare. Less than 1 out of every 100 brain tumours (less than 1%) diagnosed in England between 1995 and 2017 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
  • chemotherapy


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.

  • Cancer: Principles and Practice of Oncology (11th edition)
    VT DeVita, TS Lawrence, SA Rosenberg
    Wolters Kluwer, 2019

  • The 2021 WHO Classification of Tumors of the Central Nervous System: a summary.
    D Louis and others
    Neuro Oncology, 2021 Volume 23, Issue 8, Pages 1231-1251

  • The incidence of major subtypes of primary brain tumors in adults in England 1995-2017
    H Wanis and others
    Neuro Oncol. 2021 Volume 23, issue 8, pages 1371-1382

  • Uncommon brain tumours
    J Loeffler and G Tung
    UptoDate, accessed March 2023

  • Rare embryonal and sarcomatous central nervous system tumours: State-of-the art and future directions
    J Gojo and others
    European Journal of Medical Genetics, 2023  Volume 66, issue 1, pages 1769 - 7212  

  • 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.

Last reviewed: 
23 Mar 2023
Next review due: 
23 Mar 2026

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