A bone marrow cancer in which there is uncontrolled production of mature white blood cells called granulocytes
- More common over the age of 60
- Slightly more common in males
- Almost all cases are linked to an abnormal chromosome
- Previous exposure to radiation is a risk factor
Chronic myeloid leukaemia (CML) develops when the precursors of white blood cells known as granulocytes become cancerous and multiply. The cancerous cells are produced mostly in the bone marrow, but also in the liver and the spleen. All of the granulocytes produced function almost normally in fighting infection.
Chronic myeloid leukaemia is more common in people over the age of 60 and is slightly more common in men.
What are the causes?
The cause of CML is not known. In almost all cases, however, the cancerous cells contain an abnormal chromosome (known as the Philadelphia chromosome) in which part of one chromosome becomes attached to another. Rarely, CML is linked with past exposure to radiation, such as that used in radiotherapy.
What are the symptoms?
There are two phases of CML. In the first, or chronic, phase, lasting for about 3–5 years, the symptoms develop slowly and are usually mild. In a few cases, there may not even be any symptoms. In the second, or acute, phase, symptoms become more severe. In the chronic phase, you may experience:
Tiredness, pale skin, and shortness of breath due to anaemia.
Swelling of the abdomen due to an enlarged liver and spleen.
Joint pains due to gout, which results from the breakdown of excessive numbers of white blood cells.
During the acute phase of CML, you may also experience:
Fever and abdominal pain.
Swollen glands in the neck, armpits, and groin.
Abnormal bruising and bleeding.
Rarely, in the acute phase, skin nodules full of abnormal granulocytes appear.
What might be done?
CML is usually diagnosed by chance during the chronic phase when a blood test is carried out for another reason. In other cases, when the condition is suspected from the symptoms, a blood test will be carried out to measure the levels of blood cells. If you have CML, the test will show high numbers of granulocytes and their precursors. To confirm the diagnosis, you may have a bone marrow aspiration and biopsy to obtain tissue samples for examination.
Treatment for CML usually involves oral chemotherapy, typically with the drug imatinib, which is one of a new class of anticancer drugs known as protein kinase inhibitors. The drug interferon alfa (see Interferon drugs) may also be used. Most people who receive this treatment during the chronic phase revert to making normal blood cells (which lack the Philadelphia chromosome) and have an excellent chance of long-term survival. If oral chemotherapy is not effective, a stem cell transplant usually produces a cure.
If CML develops into the acute phase, you may be admitted to hospital to have intravenous chemotherapy treatment. Anticancer drugs may be injected directly into the bloodstream through a skin-tunnelled catheter. However, treatment rarely succeeds and the condition is usually fatal within a year.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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