Acute lymphoblastic leukaemia

Acute lymphoblastic leukaemia is a type of cancer that affects white blood cells. It progresses quickly and aggressively and requires immediate treatment. Both adults and children can be affected.

Acute lymphoblastic leukaemia is rare, with around 790 people diagnosed with the condition each year in the UK. Most cases of acute lymphoblastic leukaemia develop in children, teenagers and young adults.

Although it is rare, acute lymphoblastic leukaemia is the most common type of leukaemia that affects children. About 85% of the cases that affect children happen in those younger than 15 (mostly between the ages of 0 and 5). It affects slightly more boys than girls.

Acute lymphoblastic leukaemia is different to other types of leukaemia, including acute myeloid leukaemiachronic lymphocytic leukaemia and chronic myeloid leukaemia.

What happens in acute lymphoblastic leukaemia

All the blood cells in the body are produced by bone marrow, which is a spongy material found inside bones.

Bone marrow produces stem cells, which have the ability to develop into three important types of blood cells:

Bone marrow does not usually release stem cells into the blood until they have become fully developed blood cells. But in acute lymphoblastic leukaemia, large numbers of white blood cells are released before they are ready. These are known as blast cells.

As the number of blast cells increases, the number of red blood cells and platelet cells decreases. This causes the symptoms of anaemia, such as tiredness, breathlessness and an increased risk of excessive bleeding.

Also, blast cells are less effective than mature white blood cells at fighting bacteria and viruses, making you more vulnerable to infection.

Symptoms of acute lymphoblastic leukaemia

Acute lymphoblastic leukaemia usually starts slowly before rapidly becoming severe as the number of immature white blood cells (blast cells) in your blood increases.

Most of the symptoms are caused by a lack of healthy blood cells. Symptoms include:

In some cases, the affected cells can spread from your bloodstream into your central nervous system. This can cause neurological symptoms (related to the brain and nervous system), including:

When to get medical advice

If you or your child has some or all the symptoms listed on this page, it's still highly unlikely that acute leukaemia is the cause. However, see a GP as soon as possible because any condition that causes these symptoms needs prompt investigation and treatment.

Find out more about diagnosing acute lymphoblastic leukaemia.

What causes acute lymphoblastic leukaemia

A genetic change (mutation) in the stem cells causes immature white blood cells to be released into the bloodstream.

What causes the DNA mutation to happen is not yet understood, but known risk factors include:

Environmental factors

Extensive research has been done to determine whether the following environmental factors could be a trigger for leukaemia:

There's currently no firm evidence to suggest that any of these environmental factors increases the risk of developing leukaemia.

Cancer Research UK has more information about acute lymphoblastic leukaemia risks and causes.

Treating acute lymphoblastic leukaemia

As acute lymphoblastic leukaemia is an aggressive condition that develops quickly, treatment usually begins a few days after diagnosis.

Treatment is usually done in the following stages: 

Chemotherapy is the main treatment for acute lymphoblastic leukaemia. Other treatments you may need include antibiotics and blood transfusions. Sometimes a stem cell transplant may also be needed to achieve a cure.

Find out more about treating acute lymphoblastic leukaemia.

Complications of acute lymphoblastic leukaemia

If a cure for acute lymphoblastic leukaemia is not possible, there's a risk that the lack of healthy blood cells can make the person:

These two complications, and others, are discussed further in complications of acute lymphoblastic leukaemia.


One of the biggest factors that affects the outlook for people with acute lymphoblastic leukaemia is age. The younger a person is when they are diagnosed and treatment begins, the better the outlook.

From the available data in England it is estimated that:

Help and support

Find more information about cancer.

If you or a family member has been diagnosed with acute lymphoblastic leukaemia, Leukaemia Care provides further information, advice and support.

Call Leukaemia Care's free helpline on 08088 010 444 or email:

The charity Cancer UK also has more information about acute lymphoblastic leukaemia.

Page last reviewed: 30 September 2019
Next review due: 30 September 2022