Health condition
Chronic myeloid leukaemia
Chronic myeloid leukaemia (CML) is a blood cancer driven by the BCR-ABL fusion gene; daily targeted tablets control it so effectively that most people now live a normal or near-normal lifespan.
Why trust this guide
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Editorial team
Written by our editorial team from the UK sources listed on each page.
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Sourced from guidance
Checked against current NHS and UK specialist society guidance at the time of review.
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Current for 2026
Reviewed on 2026-09-27 with the next review scheduled for 2027-09-27.
Key facts
The essentials at a glance.
The symptoms to recognise, when to seek help, which specialist to see, and what treatment usually involves.
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Caused by the Philadelphia chromosome, which creates the BCR-ABL fusion gene
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Often found on a routine blood test showing a high white cell count
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Treated with targeted tyrosine kinase inhibitor tablets taken daily
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Response is tracked with regular BCR-ABL blood tests under a consultant haematologist
Understanding the condition
What it is and what happens next.
What causes it, how it is diagnosed, and the treatment routes available in the UK.
What it is and how it feels
CML develops when a genetic accident fuses two genes, BCR and ABL, creating an abnormal protein that drives white cell overproduction. Many people feel well at diagnosis; others notice tiredness, fullness under the left ribs from an enlarged spleen, or night sweats. The diagnosis is confirmed with blood and marrow tests that detect the fusion gene itself.
Diagnosis and treatment routes
Tyrosine kinase inhibitors such as imatinib transformed this disease from a life-threatening illness into a manageable long-term condition for most patients. Treatment response is measured with sensitive molecular blood tests at set milestones, and the drug can be switched if the response is inadequate or side effects intrude. After several years of deep, stable response, some patients are able to attempt carefully supervised treatment-free remission. If you are waiting for results or want a second opinion on a proposed plan, a private consultation with a specialist who treats this condition regularly can usually be arranged quickly, and most will review your existing scans, biopsy reports and MDT correspondence.
Seeing a specialist
Who to see, and how quickly you can be seen.
The specialist for this condition is usually a consultant haematologist. Your GP can refer you on the NHS, or you can arrange a private consultation directly.
A quiet reminder
This guide is for information, not medical advice.
Your GP knows your history and can tell you which parts apply to you. If in doubt, see them - and seek urgent care for any of the emergency symptoms described above.
Frequently asked
Common questions about Chronic myeloid leukaemia.
Quick, plain-English answers to what people ask us most.
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What is chronic myeloid leukaemia?
Chronic myeloid leukaemia (CML) is a type of blood cancer arising from a genetic change in bone marrow stem cells, causing overproduction of certain white blood cells. It is characterised by a specific genetic abnormality called the Philadelphia chromosome, which creates an abnormal protein (BCR-ABL) driving the cancer's growth. It typically progresses slowly through distinct phases if untreated, but modern targeted treatments have transformed outcomes.
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What causes CML?
It is caused by an acquired genetic change — a translocation between chromosomes 9 and 22, creating the Philadelphia chromosome — that occurs during a person's lifetime rather than being inherited. This genetic change causes the production of an abnormal protein that drives uncontrolled growth of certain white blood cells. It is not something passed on to children or inherited from parents.
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What symptoms does CML cause?
Many people are diagnosed incidentally through a routine blood test before developing symptoms. When symptoms occur, they can include fatigue, unintentional weight loss, night sweats, abdominal discomfort from an enlarged spleen, and easy bruising or bleeding. Symptoms typically develop gradually, reflecting the disease's generally slow progression in its early (chronic) phase.
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Is CML dangerous?
If untreated, CML can progress from its initial chronic phase to more aggressive accelerated and blast phases, which are much harder to treat and more dangerous. However, with modern targeted therapies (tyrosine kinase inhibitors), most people diagnosed in the chronic phase achieve excellent long-term disease control, and life expectancy now approaches that of the general population for many patients. This represents one of the most significant treatment success stories in modern cancer care.
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How is CML treated?
Treatment is primarily with targeted oral medications called tyrosine kinase inhibitors, which specifically block the abnormal protein driving the leukaemia, allowing most people to achieve excellent, long-term disease control with a good quality of life. Regular blood monitoring tracks treatment response. In select cases, including those not responding to targeted therapy, stem cell transplantation may be considered.
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Can CML be cured?
With modern tyrosine kinase inhibitor treatment, many people achieve such deep and sustained disease control that some, under careful specialist guidance, are eventually able to stop treatment without the disease returning (treatment-free remission), though this is not appropriate or successful for everyone. For most people, CML is managed as a long-term, well-controlled condition with ongoing treatment. Your haematology team can discuss what is realistic and appropriate for your specific situation.
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When should I see a specialist?
If a blood test suggests CML, prompt haematology referral is important to confirm the diagnosis and start appropriate treatment. NHS haematology referral for suspected leukaemia typically aims to be prompt; a private consultation is typically available within about 2 weeks for earlier specialist assessment if preferred.