Chronic Myeloid Leukaemia (CML)

Chronic myeloid leukaemia is a blood and bone marrow cancer that can often be controlled with targeted medicines.

CML begins when a change in a blood-forming cell leads to overproduction of certain white blood cells. It is also called chronic myelogenous leukaemia. The word chronic describes its usual pattern of development, but CML still needs prompt specialist assessment and ongoing monitoring.

Some people feel well when CML is found during a routine blood test. When symptoms occur, tiredness, reduced stamina, a feeling of fullness under the left ribs, fever, frequent infections, easy bruising or bleeding can occur. Night sweats and unexplained weight loss are common presentations of CML, but each can also have other causes.

Contact a clinician promptly for new heavy bleeding, fever with feeling unwell, breathlessness, marked weakness, or rapidly worsening symptoms. These concerns need assessment based on their severity, not on whether they point to a particular diagnosis.

CML is associated with an acquired genetic change in leukaemia cells, often called the Philadelphia chromosome. This change creates an abnormal signal that tells cells to grow and divide. It is not something a person can pass to family members through ordinary contact, and it is not caused by something they did.

CML commonly has a chronic phase, when abnormal cells are more mature and treatment may keep them under control. Without effective control, the disease can move into more active phases with increasing immature cells. Regular blood tests and molecular testing help the team see whether treatment is working and whether a change is needed.

CML is not usually linked to an inherited family pattern. It is seen more often with increasing age, and previous exposure to high-dose radiation is a recognised risk factor. Having a risk factor does not mean someone will develop CML, and many people diagnosed do not have a clear cause.

Assessment usually starts with a full blood count and review of the blood cells under a microscope. A bone marrow sample may be taken to confirm the diagnosis and examine the chromosomes. Tests for the BCR::ABL1 genetic change establish the CML subtype and provide a baseline for later monitoring.

Targeted therapy is commonly the starting treatment. These tablets block the abnormal BCR::ABL1 signal and are taken with planned blood and molecular checks. The exact medicine depends on the CML phase, other health conditions, possible interactions and how the leukaemia responds.

A stem cell transplant from a donor may be considered when CML does not respond adequately to medicines or has progressed. Transplant planning includes a detailed discussion of donor matching, conditioning treatment, infection prevention and graft-related complications.

Keep a current medicines list and tell the treating team about supplements, over-the-counter products and new prescriptions, as some can affect targeted treatments. Report side effects such as swelling, rash, diarrhoea, muscle cramps or breathlessness early so that they can be managed. Appointments remain important even when you feel well.

Care is led by a haematologist with experience in leukaemia. A pharmacist, specialist nurse and transplant team may also be involved. Bring prior blood results and a medication list to the first appointment, and ask which tests will guide treatment decisions.