Chronic myeloid leukaemia
Chronic myeloid leukaemia Content Supplied by NHS Choices

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.

CML is different to other types of leukaemia, including chronic lymphocytic leukaemia, acute myeloid leukaemia and acute lymphoblastic leukaemia.

This page covers:


When to get medical advice




Support groups and charities

Symptoms of CML

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:

  • tiredness
  • weight loss
  • night sweats
  • tenderness and swelling in the left side of your tummy
  • feeling full after small meals
  • pale skin and shortness of breath
  • a high temperature (fever)
  • bruising and bleeding easily
  • frequent infections
  • bone pain

When to get medical advice

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.

Treatments for CML

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:

  • imatinib tablets
  • nilotinib capsules
  • dasatinib tablets
  • bosutinib tablets

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.

Outlook for CML

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.

Causes of CML

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.

Support groups and charities

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:

Macmillan Cancer Support and Cancer Research UK also provide CML information and support.


Some cases of chronic myeloid leukaemia (CML) are detected during blood tests carried out for another reason.

But you should visit your GP if you have worrying symptoms of CML, such as persistent tiredness, unusual bleeding or bruising, unexplained weight loss or night sweats.

Seeing your GP

Your GP will ask about your symptoms and may carry out a simple examination to check for other problems, such as swelling in one side of your tummy.

They may also send a sample of your blood to a laboratory so it can be checked for possible causes of your symptoms.

A very high level of white blood cells in your blood could be a sign of leukaemia. If this is detected, you'll be referred to a haematologist (specialist in blood conditions) for further tests.

Confirming the diagnosis

To confirm a diagnosis of leukaemia, a sample of your bone marrow will need to be removed during a procedure called a bone marrow biopsy.

During a biopsy:

  • an area of skin at the back of your hip is numbed with local anaesthetic
  • a needle is used to remove a small sample of bone marrow
  • you may experience some discomfort while it's carried out, but it shouldn't be painful

The procedure usually takes around 15 minutes and you won't normally need to stay in hospital overnight. You may have some bruising and discomfort for a few days afterwards.

Your bone marrow will be checked for cancerous cells and the cells will be analysed to identify which type of leukaemia you have and how advanced it is.

This can help your doctors determine the best treatment for you. Read about how CML is treated.


With modern treatments, it's often possible to control chronic myeloid leukaemia (CML) for many years. In a small number of cases, it may be possible to cure it completely.

The main treatments are described below.


A medicine called imatinib is now the main treatment for CML. It's usually given soon after a diagnosis is made to slow the progression of the cancer and stop it reaching an advanced phase.

Imatinib works by reducing the production of abnormal white blood cells. It's taken as a tablet once a day.

The side effects of imatinib are usually mild and should improve with time.

They can include:

  • feeling and being sick
  • swelling in the face and lower legs
  • muscle cramps
  • a rash
  • diarrhoea

Regular blood tests and occasional tests of your bone marrow will be carried out to check whether the treatment is working. If it does work, it will usually be taken for life.


If you can't take imatinib or it doesn't work for you, a medicine called nilotinib may be recommended instead. It's also sometimes used as the first treatment for CML.

Nilotinib works in a similar way to imatinib and is taken as a capsule twice a day. If blood and bone marrow tests show the treatment is working, it's also usually taken for life.

Common side effects of nilotinib include:

If the side effects become particularly troublesome, temporarily stopping treatment usually helps to bring them under control. Treatment can then be resumed, possibly at a lower dose.


If you can't take imatinib or nilotinib, or they don't work for you, a similar medicine called dasatinib may be recommended.

This is taken as a tablet once a day and is taken for life if blood and bone marrow tests show it's working.

Side effects of dasatinib can include:

  • an increased chance of picking up infections
  • tiredness
  • shortness of breath
  • diarrhoea
  • headaches
  • a rash


Bosutinib is a similar medication to imatinib, nilotinib and dasatinib. It may be recommended if you can't take these medications, or you've tried them and they haven't helped.

Bosutinib is taken as a tablet once a day and is taken for life if blood and bone marrow tests show it is working.

Common side effects of bosutinib include:

  • diarrhoea
  • feeling and being sick
  • abdominal pain
  • a high temperature (fever)
  • a rash

For more information, see the National Institute for Health and Care Excellence (NICE) guidelines on bosutinib for previously treated chronic myeloid leukaemia.


Ponatinib is a similar medication to those mentioned above, but it's only recommended for people with a specific genetic change (mutation) called the T315I mutation.

It's taken as a tablet once a day and is taken for life if blood and bone marrow tests show it's working.

Side effects of ponatinib can include:

  • an increased risk of picking up infections
  • tiredness
  • shortness of breath
  • headaches
  • a rash
  • aching joints


Chemotherapy may be recommended if you can't take the medications above, or if CML has progressed to a more advanced stage. It may also be used while you're awaiting tests results to confirm you have CML.

Chemotherapy involves taking medication to kill the cancerous cells. Tablets are usually used first because they have fewer and milder side effects than chemotherapy injections.

Side effects can include:

  • tiredness
  • a rash
  • increased vulnerability to infection

If your symptoms persist or get worse, chemotherapy injections may be used. These have more side effects than tablets and they tend to be more severe.

In addition to the side effects mentioned above, side effects of chemotherapy injections can include:

The side effects should pass after your treatment has finished, although there's a risk that infertility could be permanent.

Stem cell or bone marrow transplants

A stem cell or bone marrow transplant is the only potential cure for CML, but it's a very intensive treatment and isn't suitable for many people with the condition.

This is where donated cells called stem cells (which produce white blood cells) are transplanted into your body so you start to produce healthy white blood cells.

A stem cell transplant involves:

  • having high-dose chemotherapy and radiotherapy to destroy the cancerous cells in your body
  • removing stem cells from the blood or bone marrow of a donor - this will ideally be someone closely related to you, such as a sibling
  • transplanting the donor stem cells into one of your veins

The high doses of chemotherapy and radiotherapy can put an enormous strain on the body and can cause significant side effects and life-threatening complications.

Transplants are generally only considered in younger people with CML, people in good general health and ideally those with a sibling who can provide a donation, as it's more likely to be successful in these cases.

But in many cases of CML, the potential risks of transplantation far outweigh the potential benefits, particularly now that treatment with imatinib can often keep the condition under control for many years.


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