Leukaemia is cancer of the white blood cells. Symptoms of leukaemia include:
- pale skin
- tiredness
- breathlessness
- having repeated infections over a short space of time
Types of leukaemia
There are two main types of leukaemia:
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acute leukaemia - where the condition progresses rapidly and aggressively and requires immediate treatment
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chronic leukaemia - where the condition progresses slowly over the course of many years and no immediate treatment is required.
The rest of this article focuses on acute leukaemia. See the separate Health A-Z topic about chronic leukaemia for more information about this condition.
Bone marrow
All of the blood cells in the body are produced by bone marrow. Bone marrow is a spongy material that is found inside the bones. It is important because it produces special cells that are called stem cells.
Stem cells are very useful because they have the ability to create other specialised cells that carry out important functions. The stem cells in bone marrow produce three important types of blood cells:
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red blood cells - which carry oxygen around the body
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white blood cells - which help fight infection
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platelets - which help stop bleeding
Usually, the bone marrow produces stem cells which are allowed to mature into ‘adult’ blood cells. However, in cases of acute leukaemia, the affected bone marrow begins to release a large number of immature white blood cells that are known as blast cells.
The immature white blood cells begin to rapidly disrupt the normal balance of cells in the blood. This means that the body does not have enough red blood cells or platelet cells. This can cause symptoms of anaemia, such as tiredness, and increase the risk of excessive bleeding.
Also, as the white blood cells are not properly formed they become less effective at fighting bacteria and viruses, making you more vulnerable to infection.
If you have acute leukaemia which is left untreated, you will not be able to survive because your blood supply will not function properly.
Types of acute leukaemia
Acute leukaemia is classified according to the type of white blood cells that are affected by cancer. There are two main types of white blood cell:
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lymphocytes - which are mostly used to fight viral infections
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myeloid cells - which perform a number of different functions, such as fighting bacterial infections, defending the body against parasites and preventing the spread of tissue damage
There are two main types of acute leukaemia that are related to the two main types of white blood cells. They are:
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acute lymphoblastic leukaemia (ALL) - which is cancer of the lymphocytes
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acute myeloid leukaemia (AML) - which is cancer of the myeloid cells
How common is acute leukaemia?
Acute leukaemia is an uncommon type of cancer.
Despite being uncommon overall, ALL is the most common type of cancer to affect children. Approximately 1 in every 2,000 children will develop ALL. About 85% of cases of ALL occur in children who are under 15 years of age, with the majority of cases developing in those who are two to five years of age.
AML is more common in older people, with most cases occurring in people who are 50 years of age or over. For reasons that are not fully understood, acute leukaemia is more common in boys and men than it is in girls and women.
The cause or causes of acute leukaemia are uncertain, but known risk factors include:
- exposure to high levels of radiation
- exposure to benzene, which is a chemical that is used in manufacturing and it is also found in cigarettes
Outlook
The outlook for children with ALL is usually good. Almost all children will achieve a remission (a period of time where they are free from symptoms) from their symptoms, and 85% will be completely cured. The outlook for adults with ALL is less promising as only 40% of people will be completely cured.
The outlook for people with AML varies because there are a number of sub-types of AML, and some sub-types are more challenging to treat than others. Some types of AML have a 75% cure rate, while others only have a 20% cure rate. Younger people with the condition tend to have a better outcome than older people.
Treatments for acute leukaemia usually involve a combination of chemotherapy and radiotherapy. In some cases, a bone marrow transplant may also be used in order to achieve a cure.
If a cure is not possible, there is a risk that the lack of healthy blood cells can make people extremely vulnerable to life threatening infections (due to the lack of white blood cells), or uncontrolled and serious bleeding (due to the lack of platelets).