Leukaemia is cancer of the white blood cells. Symptoms of leukaemia include:
- pale skin
- tiredness
- breathlessness
- 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 leukaemia progresses rapidly and aggressively and requires immediate treatment
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chronic leukaemia - where the leukaemia progresses slowly over the course of many years and no immediate treatment is required
The rest of this article focuses on chronic leukaemia. See the separate Health A-Z topic about Acute leukaemia form more information about this condition.
Bone marrow
All of the blood cells in your body are produced in your bone marrow. Bone marrow is a spongy material that is found inside the bones. It is important because it produces special cells that are known as 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
In leukaemia, the cancer begins in the stem cells and causes them to produce more white blood cells than are needed. Over time, the cancerous white blood cells build up, disrupting the normal balance of cells in the blood.
This means that the body does not have enough red blood cells or platelets. This can cause symptoms of anaemia, such as tiredness, as well as increasing the likelihood of excessive bleeding.
Also, as the white blood cells are not properly formed, they are less effective at fighting bacteria and viruses. This increases a person’s vulnerable to infection.
Types of chronic leukaemia
Chronic leukaemia is classified according to what type of white blood cells 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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chronic lymphocytic leukaemia (CLL) - which is cancer of the lymphocytes
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chronic myeloid leukaemia (CML) - which is cancer of the myeloid cells
How common is chronic leukaemia?
Chronic leukaemia is an uncommon type of cancer.
CLL is most common in older people, with most cases developing in people who are over 55 years of age. CML is most common in people who are 40 to 60 years age.
The exact cause of chronic leukaemia is uncertain, although known risk factors include:
- exposure to high levels of radiation
- exposure to the chemical, benzene
Chronic leukaemia can be cured using a bone marrow transplant. However, not everyone is a suitable candidate for transplantation.
Outlook
The outlook for CML depends to a large extent on how well a person responds to treatment with a new type of medication called imatinib. For people who respond well, the outlook is good, and it has been estimated that they may live up to 20 years after a receiving a diagnosis.
The use of imatinib only became widespread after 2001, so information about how it affects long-term survival rates in people with CML is unavailable.
Unfortunately, some people do not respond to imatinib, and an estimated 35% of them will live for five years or more after receiving their diagnosis.
The outlook for CLL is moderate to poor, with 44% of men and 52% of women living at least five years after being diagnosed.