All of the blood cells in the body are produced by bone marrow, a spongy material found inside bones.
Bone marrow produces specialised cells called stem cells, which have the ability to develop into three important types of blood cells:
Normally, bone marrow doesn't release stem cells into the blood until they are 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.
Acute lymphoblastic leukaemia usually starts slowly before rapidly becoming severe as the number of immature white blood cells in your blood increases.
Most of the symptoms are caused by the lack of healthy blood cells in your blood supply. Symptoms include:
In some cases, the affected cells can spread from your bloodstream into your central nervous system. This can cause a series of neurological symptoms (related to the brain and nervous system), including:
If you or your child has some or even all of the symptoms listed above, it's still highly unlikely that acute leukaemia is the cause. However, see your GP as soon as possible because any condition that causes these symptoms needs prompt investigation and treatment.
Read more about diagnosing acute lymphoblastic leukaemia.
It is a genetic change (mutation) in the stem cells that causes immature white blood cells to be released into the bloodstream.
It's not clear what causes the DNA mutation to occur, but known risk factors include:
Extensive research has been carried out 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.
As acute lymphoblastic leukaemia is an aggressive condition that develops rapidly, treatment usually begins a few days after diagnosis.
Treatment is usually carried out in the following stages:
Chemotherapy is the main treatment for acute lymphoblastic leukaemia. Other treatments you may need include antibiotics and blood transfusions. In some cases, a bone marrow transplant may also be needed to achieve a cure.
Read more about treating acute lymphoblastic leukaemia.
If a cure for acute lymphoblastic leukaemia isn't possible, there's a risk that the lack of healthy blood cells can make the person:
These two complications, plus a number of others, are discussed further in complications of acute lymphoblastic leukaemia.
The outlook for children with acute lymphoblastic leukaemia is usually good. Almost all children will achieve remission (a period of time where they're free from symptoms), and 85% will be completely cured.
The outlook for adults with acute lymphoblastic leukaemia is less promising. Around 40% of people aged between 25 and 64 will live for five years or more after receiving their diagnosis. In those aged 65 or over, around 15% will live for five years or more after being diagnosed.
Cancer Research UK has more detailed survival statistics for acute lymphoblastic leukaemia.
If you or a family member has been diagnosed with acute lymphoblastic cancer, Leukaemia Care can provide further information, advice and support.
You can call their freephone helpline – 08088 010 444 – or email: firstname.lastname@example.org