What is T-cell acute lymphoblastic leukaemia (T-ALL)?

• T-cell acute lymphoblastic leukaemia (T-ALL) is a type of blood cancer that affects your T-lymphocytes.
• It’s very important to start treatment soon after you have been diagnosed, because T-ALL can develop quickly.
• Your treatment plan will be individual to you. Your doctor will carefully consider the risk of your T-ALL coming back when planning each phase of your treatment.
• There will be times where you will be more at risk of infection.

T-cell acute lymphoblastic leukaemia (T-ALL) is a type of acute lymphoblastic leukaemia that affects your T-lymphocytes. T-lymphocytes are a type of white blood cell that helps fight infection. If you have T-ALL, too many of these white blood cells are made by your bone marrow. These cells don’t work as they should, and as they build up, these leukaemia cells crowd out the healthy blood cells in your blood and bone marrow.

This stops your blood from doing the things it needs to do to keep you healthy, like fighting off infections and carrying oxygen around your body.

T-ALL is a fast-growing type of blood cancer, which means that it's important that it's diagnosed and treated quickly.

• T-ALL is less common than B-ALL. There are around 150 new cases of T-ALL a year in the UK.
• T-ALL is more common in people under the age of 40. It’s more common in males than females.
• You can’t give T-ALL to someone else, and you can’t pass it down to your children (it isn’t hereditary).
• It’s important to know that none of your lifestyle choices have caused you to be diagnosed with T-ALL.

If you or a loved one has been diagnosed with T-ALL, you might find it an overwhelming and shocking experience. It’s totally normal if you're feeling numb, anxious, and unable to process everything at once.

Things will likely move quite fast after your diagnosis, and not leave much time for it to sink in. You may have never heard of T-ALL before, leaving you with lots of questions about your diagnosis, and what will happen next. Don’t be afraid to speak to your hospital team about your questions and ask them to explain anything you don't understand.

You should be given a key worker. This is your main point of contact at your hospital and is often a clinical nurse specialist (CNS). They can answer any questions you have. You have a right to ask for a key worker.

You and your loved ones may find it helpful to read our information on these topics:

• mind and emotions, including self-help tips and how to find support
• money, work and other practical advice
• guidance on eating well with blood cancer
• the benefits of keeping active
• information for family and friends.

Our Support Service is here for you if you need to talk things through at any point. Family and friends can contact us too. You can contact our dedicated, friendly team of nurses on 0808 2080 888 or at [email protected]

After you have been diagnosed with T-ALL, you may want to know more about your prognosis.

There are some other things that we know can affect prognosis, such as:

• your age, general level of fitness and whether you have any other serious health problems
• how well your body may be able to cope with intensive treatment
• whether the T-ALL has spread to your brain or spinal cord
• The exact type of T-ALL you have and whether there are certain gene changes on the leukaemia cells which could make it harder to treat
• how well your first round of treatment works to get the T-ALL into remission.

It's important to remember, that even after taking these factors into account, people can still have quite different experiences. Everyone is different and so everyone’s prognosis is individual.

Thank you to Professor Adele Fielding for supporting with the creation of this information and checking the clinical accuracy.

This information was first published in June 2026. Next full review due June 2029. We may make factual updates between reviews.