Chronic myeloid leukaemia (CML) is a type of cancer that affects the white blood cells and tends to progress slowly over many years.
It can occur at any age, but is most common in older adults around 60-65 years of age.
In CML, the spongy material inside some bones (bone marrow) produces too many myeloid cells – immature white blood cells that aren't fully developed and don't work properly.
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CML doesn't usually have any symptoms in its early stages and may only be picked up during tests carried out for another reason.
As the condition develops, symptoms can include:
See your GP if you have any persistent symptoms that you're worried about.
The symptoms above can have many different causes, so it's unlikely you have CML, but it's a good idea to get them checked out.
Your GP can arrange for a blood test to check for possible causes of your symptoms. If this detects a problem, you may be referred to a hospital specialist for further tests.
Read more about how CML is diagnosed.
Treatment for CML is usually started straightaway to help slow down its progression and keep it under control.
The main treatments for CML are medications called tyrosine kinase inhibitors that stop the cancer cells growing and multiplying. They can help keep CML under control if taken for life.
These medicines include:
Regular blood tests will be carried out to check the medication is working.
Occasionally, it may be possible to have a stem cell transplant. Stem cells are cells that go on to form other types of cell. In this case, stem cells from your bone marrow are transplanted, which can produce healthy white blood cells.
A stem cell transplant can potentially cure CML, although it's a very intensive treatment and isn't suitable in many cases.
Read more about how CML is treated.
CML is a serious and life-threatening condition, but with the introduction of newer tyrosine kinase inhibitors, the outlook is much better now than it used to be.
It's estimated that around 85-95% of people will now live at least five years after their diagnosis, and that many people will probably live much longer than this.
It's thought life expectancy may not be affected at all in some cases, as long as treatment is continued.
The outlook is generally better the earlier CML is diagnosed.
CML is caused by a genetic change (mutation) in the stem cells produced by the bone marrow.
The mutation causes the stem cells to produce too many underdeveloped white blood cells. It also leads to a reduction in the number of other blood cells, such as red blood cells.
The change involves bundles of DNA called chromosomes. Within each stem cell, a section of DNA from one chromosome swaps with a section from another. This change is known as the "Philadelphia chromosome". Read more about genes and chromosomes.
It's not known what causes this to happen, but it's not something you're born with and you can't pass it on to your children.
Living with a serious, long-term condition such as CML can be very difficult.
You may find it useful to find out as much as you can about the condition and speak to others affected by it.
The following support groups and charities can offer help and advice for people CML, their families and their carers: