Chronic Myeloid Leukaemia (CML) is a blood cancer that develops slowly over many years.

NHS nurse in leukaemia treatment centre

What is CML?

Chronic myeloid leukaemia (CML) is one of four types of leukaemia. It is a cancer that affects white blood cells, and, because it is chronic rather than acute, CML tends to develop slowly over many years.

While it can occur at any age, it is most common in older adults around 60-65 years of age.

What causes Chronic Myeloid Leukaemia?

CML develops when the bone marrow produces too many under-developed myeloid blood stem cells. These are white blood cells that haven’t developed properly, and do not function as normal*. They over-populate the bone marrow so that it can’t make healthy blood cells and eventually spill into the blood, spreading the cancer.

Of the roughly 8,600 people who are diagnosed with leukaemia each year in the UK, approximately 750 of these have CML. It is quite a rare condition and is more common in men than women.

What are the symptoms of CML?

While 1 in 4 patients will have no symptoms when diagnosed with Chronic Myeloid Leukaemia, symptoms can include:

  • weight loss
  • tiredness 
  • abnormal bruising or bleeding
  • bone pain
  • swollen lymph glands.

Imatinib and CML treatments

While CML is very rare, medicines called tyrosine kinase inhibitors (TKI) can help control the cancer. Imatinib, a TKI, is currently the main treatment for CML and works by slowing the production of abnormal white blood cells. Sometimes it is administered in conjunction with chemotherapy.