Chronic myeloid leukaemia (CML) is a serious condition, but if it’s caught in the early stage, it’s possible to do well on treatment for many years.

‘Chronic’ means CML can take a long time to develop, and ‘myeloid’ tells you that it affects a particular group of white blood cells.

CML develops because your body’s process for making white blood cells goes wrong. You can learn more about white blood cells and this process, called haematopoiesis, in our general information about leukaemia.

What are the symptoms of CML?

Many people with CML don’t feel unwell at first. The symptoms of CML can include:

  • tiredness
  • night sweats
  • swelling in your abdomen
  • pale skin
  • breathlessness
  • fever
  • bruises
  • unusual bleeding
  • frequent infections
  • aching arms and legs.

What causes CML?

We don’t know what causes CML. It’s most likely to affect people aged between 60 and 65. It happens more often in men than in women.

Most people with CML have what’s called ‘the Philadelphia chromosome’ in their cancer cells. Despite the way its sounds, CML is not passed down through the family.

How is CML diagnosed?

Because it doesn’t always cause symptoms at first, CML is often picked up when you have a blood test for another reason.

If CML is suspected, you’ll be offered more blood tests and a bone marrow biopsy to confirm the diagnosis.

Later on, you’ll be offered these tests regularly to monitor how well your treatment is working.

You can read more in our information about tests for leukaemia.

What are the phases of CML?

CML can progress over time, which happens in three phases:

  • Chronic phase. The cancer is progressing slowly. The outlook is best in this phase and with treatment, CML does not go any further for most people.
  • Accelerated phase. The cancer progresses more quickly. The bone marrow is making too many immature white blood cells (called blasts), but the number is still relatively small.
  • Blast phase or blast crisis. The cancer becomes more aggressive and transforms into an acute leukaemia. At this stage, the bone marrow becomes filled with immature white blood cells (blasts) in much greater numbers and there are also more blasts in the blood . This phase can progress more quickly and you can feel quite unwell.

What is the treatment for CML?

The main treatment for CML is a group of drugs called tyrosine kinase inhibitors

(TKIs). These include:

  • Imatinib (Glivec)
  • Nilotinib (Tasigna)
  • Dasatinib (Sprycel)
  • Bosutinib (Bosulif)
  • Ponatinib (Iclusig)

If a TKI is working well, most people carry on taking it as a lifelong treatment.

Other drugs that are sometimes used to treat CML are:

  • Hydroxycarbamide (Hydrea)
  • Interferon alfa (IntronA, Roferon-A)

If you’re unable to take a TKI, it’s not working, or you’re in a more advanced phase of CML, your doctor might recommend chemotherapy.

In a few cases, a stem cell transplant (also known as a bone marrow transplant) is a possibility. The procedure can be very hard on your body so it’s not suitable for everyone.

Joining a clinical trial may be an option, and supportive care also helps you feel better.

What is the outlook (survival) for CML?

Survival depends on many factors, so no one can tell you for sure what will happen in your individual case. Partly, the outlook depends on the stage of your CML, and your age (younger people have higher survival rates).

Survival rates for people with CML have improved dramatically in the past 20 years due to TKI treatment, and the outlook is good for most people, particularly if the condition is diagnosed in the chronic phase.

On average for CML, about 7 in 10 people live for five years or more after their diagnosis. Unfortunately, it is harder to treat blast phase CML, and the outlook will depend on specific factors in your case.

Whatever your situation, there’s lots of emotional and practical support available. Find out more in our information on living with leukaemia.