Chronic myeloid leukaemia (CML) is blood cancer that starts in the blood-forming myeloid cells or stem cells in your bone marrow. CML is a slow-growing type of blood cancer that develops over a long time and causes your bone marrow to make too many abnormal white blood cells.
There are three phases of CML:
Chronic phase (by far the most common)
Accelerated phase
Blast phase (also called blast crisis)
You can have CML without having noticeable symptoms.
Symptoms can be similar to those caused by other illnesses and tend to be mild at first and get worse slowly.
If you do have symptoms, they can include:
Feeling full or pain in your tummy (abdomen)
Swelling of your lymph nodes
Feeling weak or tired
Weight loss
Heavy sweating at night
High temperature (fever)
Pain in your bones or joints
Picking up infections more often than usual
Bruising and bleeding easily
Loss of appetite
People with CML have an acquired genetic mutation in myeloid stem cells growing in their bone marrow, caused by the Philadelphia (Ph) chromosome—a rearrangement of genetic material between chromosomes 9 and 22.
The region where chromosome 9 joins chromosome 22 creates a new gene, called BCR-ABL.
Known risk factors to CML include ageing, which increases the likelihood of genetic mutations, and previous radiation therapy or accidental exposure to high levels of environmental irradiation.
Your doctor may suspect you have CML if you have unusual blood test results.
Blood tests, molecular testing, and chromosome analysis are used for diagnosis.
Common tests for CML include:
Your doctor will check for high levels of white blood cells or low red blood cell levels.
Your doctor will take small samples of fluid or tissue for genetic tests. A medical pathologist will perform tests to analyse abnormal cells’ genetic makeup.
Your doctor will use this test to determine if CML is affecting other parts of your body.
Your doctor may do this test to determine if your spleen is larger than normal. An enlarged spleen is a CML symptom.
Every CML patient requires a multidisciplinary individualised treatment approach comprising both psychosocial support and medical treatment.
The main aim of your treatment is to achieve long-term control of the CML so the signs of the disease reduce or disappear. This is known as remission. Another goal is to stop the CML from progressing to a more advanced phase.
There are several kinds of treatment for CML:
The most common treatment for CML, block the abnormal tyrosine kinase protein from the Philadelphia chromosome and have transformed its treatment and prognosis
Which uses cytotoxic agents to kill or slow leukaemia cells, is rarely used in CML and mainly given in advanced phases
Like blood transfusion for anaemia (only if needed)
Rarely used in CML, may be offered in advanced phases when targeted therapy or chemotherapy no longer work
Your treatment team will explain the treatments, their benefits and possible side effects
CML usually progresses slowly, and many people have it for years without symptoms, often discovering it through routine blood tests. Prompt treatment helps prevent progression, but without treatment it can become life-threatening within three to four years.
If you have CML, you’ll likely need lifelong medication and regular checkups so your doctor can monitor your health, watch for recurrence, and check for second cancers.In general, you should expect to see your doctor every few months for the rest of your life.
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Content ID: FA-11681571. Approval date: 19 May 2026. Expiry date: 19 May 2028.