Chronic myeloid leukaemia (CML): symptoms, diagnosis and treatment

Chronic myelogenous leukaemia and chronic myeloid leukaemia are two names for the same disease, abbreviated CML. Cancer Research UK explains that CML is a cancer of the blood and bone marrow that develops from early white blood cells called myeloid stem cells, usually very slowly. Leukaemia is a blood cancer in which abnormal white blood cells are made in the bone marrow, do not develop properly and do not protect you from infection as they should.

Leukaemias are divided into acute (fast-developing) and chronic (slow-developing) types. Cancer Research UK says in chronic leukaemia the white blood cells are almost fully developed but not completely normal, and the body makes too many of them. The three main chronic leukaemias are chronic lymphocytic leukaemia (CLL), CML and hairy cell leukaemia. In CML the abnormal cells develop from myeloid stem cells that go on to become neutrophils, the most common white blood cell.

Cancer Research UK says that around 900 people are diagnosed with CML in the UK each year, and that although it can be diagnosed at any age, it is more common in older people.

Cancer Research UK says many people with CML do not have any symptoms at all and are diagnosed because they have a routine blood test for something else. The symptoms tend to be mild at first and get worse slowly, and they can be similar to those caused by other illnesses. Most people with these symptoms will not have CML, but they should be checked by a GP.

• Tummy discomfort or feeling full, because the spleen (under the ribs on the left) becomes swollen. Lymph nodes can also swell.

• Tiredness and looking pale, from anaemia as abnormal white cells crowd out red blood cells.

• Weight loss and poor appetite, even if you think you are eating normally.

• A high temperature or sweating, often at night.

• Bone or joint pain.

• Infections that will not get better.

• Easy bruising or bleeding, such as nosebleeds or bleeding gums, from low platelets.

Cancer Research UK lists headaches and eyesight changes such as blurred vision among less common symptoms, usually in later stages, when a very high white blood cell count can clog the smallest blood vessels. It also names priapism, a persistent painful erection that will not go down, as a rare symptom that is an emergency: an erection lasting too long can cause permanent damage and needs medical attention.

If you have any of the symptoms above, or symptoms that are unusual for you or will not go away, see your GP. Cancer Research UK stresses that symptoms are unlikely to be cancer, but it is important to get them checked.

Cancer Research UK says we do not know what causes most cases, but exposure to high-energy radiation can increase risk. The underlying change is genetic: the ABL1 gene on chromosome 9 breaks off and sticks to the BCR gene on chromosome 22, creating a fusion gene called BCR-ABL1. This makes the cell produce too much of a protein called tyrosine kinase, which encourages leukaemia cells to grow and multiply.

The changed chromosome 22 looks shorter than normal and is called the Philadelphia chromosome. Cancer Research UK says most people with CML have it, and that doctors use it to diagnose CML and to monitor response to treatment. The gene change happens by chance when a cell divides: it is not inherited, so you were not born with it and it cannot be passed on to your children.

Cancer Research UK says you usually start by seeing your GP if you have symptoms, or your GP may contact you after an abnormal blood test. The GP may do a physical examination and blood tests, then refer you to a haematologist (a blood specialist) at hospital, sometimes quickly.

Hospital tests can include repeat blood tests, genetic tests, a bone marrow test, immunophenotyping, tests for infection, a chest X-ray and an ultrasound scan. The genetic tests look for the BCR-ABL1 change. A FISH test, which tags the BCR and ABL1 genes with dyes, is usually the first genetic test because it is quicker. Cytogenetic and PCR tests are also used, and PCR is later used to monitor response. Bone marrow samples are usually taken from the back of the hip bone under local anaesthetic.

Because CML and its treatment can weaken the immune system, you will also have blood tests for viruses such as HIV, hepatitis B and hepatitis C before treatment starts.

Instead of stages, doctors use phases for CML. Cancer Research UK says the main system describes three phases, and that knowing the phase helps your doctor decide which treatment you need. Doctors look at the number of immature white blood cells (blasts), the number of white blood cells and platelets, and chromosome changes in the leukaemia cells.

Cancer Research UK says targeted cancer drugs called tyrosine kinase inhibitors (TKIs) are the main treatment for CML. They work by switching off the tyrosine kinase produced by the BCR-ABL1 gene. Blood Cancer UK says the majority of people with CML take a daily tablet, a TKI, and that most people with CML can live a normal life with treatment.

Cancer Research UK lists the other parts of treatment: chemotherapy for some people, stem cell or bone marrow transplants (usually using donor stem cells), regular tests during treatment to monitor response, and supportive treatments to prevent or control problems caused by CML and its treatment. It also notes that some people are able to stop treatment if their CML is well controlled, which doctors may call treatment-free remission.

Your haematology team will explain which TKI is suitable, the side effects, and how often you will be monitored. Do not stop or change a tablet without speaking to your team.

Cancer Research UK describes CML as often a slowly developing condition that treatment can keep under control for many years, and says survival depends on several factors including age, with figures giving only a general guide. Blood Cancer UK describes prognosis as something your doctor can discuss with you based on your own circumstances.

Support is available. Cancer Research UK and Blood Cancer UK provide information and support lines, and the clinical nurse specialist in your haematology team is a key contact. Mental health can also be affected by a cancer diagnosis, and it is reasonable to raise this with your team.

On the NHS, CML is diagnosed and treated by haematology teams, usually after a GP or an abnormal blood test result prompts referral, with long-term monitoring by blood and bone marrow tests. Some people seek a private haematology opinion for speed or a second view. The diagnostic tests, TKI treatment and monitoring are the same, and any private results should be shared with your NHS team.