Atypical teratoid rhabdoid tumour (AT/RT)

What is an atypical teratoid rhabdoid tumour (ATRT)?

ATRTs are classified as embryonal tumours, meaning that they develop from stem cells that helped the embryo to form in the womb, but have unfortunately remained active in the brain after birth. When these stem cells fail to stop dividing and developing after the child is born, they can form a cancerous tumour.

Where do atypical teratoid rhabdoid tumours (ATRTs) occur?

Atypical teratoid rhabdoid tumours (ATRTs) can be found anywhere in the brain or spinal cord, which together make up the central nervous system (CNS). They tend to begin in the brain and spread to the spinal cord rather than beginning in the spinal cord, although this has been reported in some cases. 

For some patients, other forms of rhabdoid tumours may also be discovered in the kidney and other soft tissues, so a full body MRI scan is likely to be offered in order to clarify the full diagnosis. 

Atypical teratoid rhabdoid tumour (ATRT) classification

Atypical teratoid rhabdoid tumour (ATRT) is usually classified as a World Health Organisation (WHO) Grade 4 tumour, which means that it is a fast-growing form of brain cancer. Due to the rarity of this tumour, there is no standard staging system, so tumours are simply described as either newly diagnosed or recurrent.

Due to their similar appearance under a microscope, atypical teratoid rhabdoid tumours (ATRTs) often used to be diagnosed as Primitive Neuroectodermal tumours (PNETs) or as Medulloblastomas before the introduction of SMARCB1 and SMARCA4 as molecular markers, which sets them apart from these closely related paediatric brain tumours.  SMARCB1 and SMARCA4 are both tumour suppressor genes. Changes in the DNA of these genes means that they then fail to give the signal for a protein to be produced that controls cell growth, and so the body is unable to stop or “suppress” tumours from forming.

Recent research has highlighted three subgroups of atypical teratoid rhabdoid tumours, each with distinct clinical and molecular characteristics: meaning the symptoms that they present within the child, and how they can be categorised using the type of genetic profiling mentioned above. Each subgroup of ATRT tumours offers different options for personalised treatment, and researchers are working to establish the best treatment combination for each tumour, so discussing clinical trial options with the patient’s medical team is a route that is often taken by parents of children with this tumour type.

What causes an atypical teratoid rhabdoid tumour (ATRT)?

The development of an atypical teratoid rhabdoid tumour (ATRT) is generally agreed by scientists to be caused by mutations in the DNA of two genes that help to control cell growth. Known as “tumour suppressor genes”, they have been given the names SMARCB1 and SMARCA4 and are explained in more detail above.

Such genetic changes may be spontaneous (appearing for the first time in a family) or inherited. For example, the inherited genetic condition schwannomatosis may predispose someone to develop an ATRT tumour.

If the genetic mutation is inherited, the risk of rhabdoid tumours forming in different parts of the body (for example the kidneys) as well as in the brain is increased.  However, reports to date of the tumour being diagnosed in more than one family member are extremely rare.

What are the symptoms of an atypical teratoid rhabdoid tumour (ATRT)?

The symptoms vary according to the tumour location and the age of the patient, which sometimes makes this tumour difficult to diagnose. However because these are fast-growing tumours, the symptoms can both appear and progress quickly. In infants you may see an increase in the size of the head, and for patients of all ages the most common symptoms are:

•Headaches, particularly after having laid down and slept all night
•Changes in activity levels
•Loss of balance

You can read more about brain tumour symptoms here.

Discover more about how a brain tumour is diagnosed.

What treatment is available for atypical teratoid rhabdoid tumours (ATRTs)?

The first line of treatment would usually be surgery, in order to remove as much of the tumour as possible and to obtain a biopsy (a sample of the tumour tissue that can then be analysed in a laboratory).

Guided by the age of the patient, the position of the tumour, how much tumour remains and the results of the biopsy, surgery is usually followed by chemotherapy and radiotherapy, sometimes with the addition of specialised drugs designed to target the particular molecular markers of the patient’s tumour type.

Atypical teratoid rhabdoid tumour (ATRT) prognosis

Atypical teratoid rhabdoid tumour (ATRT) is a very difficult tumour to treat and, unfortunately, the outcomes remain poor with survival times varying from a few months to a few years between individuals. The number of patients surviving for 5 years is around 32% of those diagnosed.

In general, the older that children are at the point of diagnosis, the better their prognosis is likely to be. Those who are diagnosed before tumours have spread, and those for whom most of the tumour can be removed by surgery, have a better chance of longer-term survival.

Frequently asked questions

Is an atypical teratoid rhabdoid tumour (ATRT) cancer?

Yes unfortunately all ATRTs are classified as grade 4, which means that an atypical teratoid rhabdoid tumour (ATRT) is a malignant, fast-growing form of brain cancer.

Who is most likely to be diagnosed with an atypical teratoid rhabdoid tumour (ATRT)?

Atypical teratoid rhabdoid tumours (ATRTs) are the most common malignant form of brain tumours in children under 1 year old.

They are most often diagnosed in infants and toddlers when they are only 1 or 2 years old.

They represent approximately 1–2% of all paediatric brain tumours in children up to 16 years old.

Very rarely, they can be diagnosed in adults: for example, of the approximately 58 people diagnosed globally per year, only 2 are likely to be in adults over 16 years old.

How can we find a cure for atypical teratoid rhabdoid tumours (ATRTs) in the UK?

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

Our team at the University of Plymouth Low-Grade Brain Tumour Research Centre 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 in children and adults, including schwannomasmeningiomas and low-grade gliomas.

The team of research and clinical experts in our Research Centre at Imperial College, London, are studying the way in which the ketogenic diet works in brain cancer, which may have the potential to influence a wide range of brain tumours.

Pioneering research at our Brain Tumour Research Centre at Queen Mary University of London is focused on using GBM stem cells to help develop unique, patient-specific treatments. Their findings are expected to translate into other types of adult and paediatric brain tumours in the future.

We also fund BRAIN UK at Southampton University, the country’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 ATRT brain tumours.