Overview
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 are not fully developed and do not work properly.
CML is different to other types of leukaemia, including chronic lymphocytic leukaemia, acute myeloid leukaemia and acute lymphoblastic leukaemia.
Symptoms of CML
CML does not usually cause 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
- 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.
These type of symptoms 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.
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 medicines 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 is not suitable in most cases.
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 70% of men and 75% of women will live for at least 5 years after their diagnosis. Younger adults tend to have a better outlook than older adults.
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 cannot 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.
Treatment
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.
Imatinib
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.
Nilotinib
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.
Dasatinib
If you cannot take imatinib or nilotinib, or they do not 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
Bosutinib is a similar medication to imatinib, nilotinib and dasatinib. It may be recommended if you cannot take these medications, or you've tried them and they have not 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
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
Combination therapy
In some cases, a combination of these medicines may be recommended. For example, a combination of high-dose imatinib, dasatinib and nilotinib may be recommended for people who did not respond to normal-dose imatinib.
Chemotherapy
Chemotherapy may be recommended if you cannot take the medicines 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 is not 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.
Clinical trials
In the UK, a number of clinical trials are underway that aim to find the best way to treat leukaemia. Clinical trials are studies that use new and experimental techniques to see how well they work in treating and possibly curing diseases.
You should be aware there's no guarantee the techniques being studied in the clinical trial will be more effective than current treatments.
Your care team will be able to let you know whether there are any clinical trials available in your area, as well as explaining the benefits and risks involved.