Chronic myeloid leukaemia

Doctors don't know exactly what causes chronic myeloid leukaemia (CML). But some risk factors can raise your chance of developing it.

Chronic myeloid leukaemia (CML) can develop at any age, but it becomes more common as people get older. In the UK, over half of the people diagnosed with CML are over the age of 60.

Chronic myeloid leukaemia (CML) is slightly more common in men and people assigned male at birth than in women and people assigned female at birth. Doctors don't know why this is.

Being exposed to very high levels of radiation raises the risk of chronic myeloid leukaemia (CML). This could happen after a nuclear accident, for example. Very few people are ever exposed to radiation at a level high enough to raise their risk of CML.

Research has found no link between the risk of developing CML and:

• living near nuclear power stations
• exposure to electro-magnetic fields
• living near high-voltage electricity cables
• household radon (a naturally occurring gas)

If you have symptoms, you'll usually start by seeing your doctor, who will examine you. If they think you may have chronic myeloid leukaemia (CML), they'll refer you to a haematologist for more tests. A haematologist is a doctor who specialises in diagnosing and treating blood problems.

The haematologist will ask about any illnesses or health problems you've had. They'll check whether your spleen is enlarged, and they'll arrange tests.

You may have the following tests.

You'll have blood tests at the hospital. These tests will:

• check the numbers of blood cells in your blood, which is called a full blood count (FBC)
• look for leukaemia cells

If leukaemia cells show up in your blood, the haematologist will arrange more tests. These will find out what type of leukaemia you have and what phase it is. That helps your doctors plan your treatment.

In a bone marrow biopsy, a doctor or nurse takes a small sample of bone marrow and tests it for abnormal white blood cells. This test is used in chronic myeloid leukaemia. The sample usually comes from the back of the hip bone (the pelvis). Rarely, it's taken from the breast bone (the sternum).

If you have chronic myeloid leukaemia, your doctor may ask for an ultrasound scan to check the size of your spleen and liver. The scan uses sound waves to build up a picture of the inside of your body. It doesn't hurt, and it takes around 10 to 15 minutes.

Cytogenetic and molecular tests look for gene changes (mutations) inside the leukaemia cells. The tests may include:

Doctors take samples of your blood and bone marrow, and then they test those samples to look for the Philadelphia chromosome.

The polymerase chain reaction (PCR) test is a blood test that looks for the BCR-ABL1 gene in leukaemia cells. It's very sensitive, so it can pick up tiny amounts of leukaemia.

If you're diagnosed with chronic myeloid leukaemia (CML), you'll have PCR blood tests regularly. Doctors use them to check how well your treatment is working.

PCR tests can also find extra gene changes, called mutations, in the BCR-ABL1 gene. Some of these changes can tell your doctor how well targeted therapy drugs are likely to work for you. These drugs are called tyrosine kinase inhibitors (TKIs). One change the test looks for is the T3151 gene change.

PCR can detect very small amounts of BCR-ABL, even when cytogenetic testing doesn't find the Philadelphia chromosome.

The treatment you have for chronic myeloid leukaemia (CML) depends on which phase the illness is in. CML usually develops slowly.

There are 3 phases of CML:

• chronic phase
• accelerated phase
• blast phase

Doctors work out the phase from two things:

• the number of immature blood cells (blast cells) in your blood and bone marrow
• your symptoms

Most people are diagnosed when CML is still in the chronic phase.

When chronic myeloid leukaemia (CML) is in the chronic phase, you may have no symptoms at all. Most people can live a normal life. Treatment is tablets that you can take at home, and you'll have regular blood tests to check how well it is working.

For most people, the leukaemia can be well controlled for as long as treatment continues.

In the chronic phase, less than 15 in 100 blood cells in the blood or bone marrow (15%) are blast cells.

In a small number of people, chronic myeloid leukaemia (CML) moves from the chronic phase into the accelerated phase. This can happen if the CML doesn't respond well to treatment. Some people are already in the accelerated phase when they are first diagnosed.

In the accelerated phase, less than 20 in 100 blood cells in the blood or bone marrow (10% to 19%) are blast cells. So there are more blast cells in the blood or bone marrow than before. You may also develop some of the more common symptoms of leukaemia.

If you feel unwell or develop new symptoms, tell your doctor.

Relapse in chronic myeloid leukaemia (CML) means the leukaemia cells have come back after a time in remission, when there were no signs of them. Doctors usually find this with the PCR test.

Along with the phase of chronic myeloid leukaemia (CML), your cancer doctor will work out a risk score for you. This helps them plan the best treatment for you.

Risk scores are based on:

• your age
• the size of your spleen
• the number of blast cells in your blood
• your platelet count

Depending on the score, people with CML are put into 3 risk groups:

• low
• intermediate
• high

Knowing your risk group gives your haematologist an idea of how likely the CML is to respond well to treatment. Still, most people with CML respond to tyrosine kinase inhibitor drugs (TKIs) regardless of their risk score.

A team of specialists will meet to discuss the best treatment for you. This is called a multidisciplinary team (MDT).

Your haematologist or specialist nurse will explain the different treatments and their side effects. They will also talk with you about the things to think about when you make treatment decisions. You'll need all this information before you give your permission (consent) to have any treatment.

The aim of treatment for chronic myeloid leukaemia (CML) is to put the disease into remission and keep it there. This means there are no signs of CML in your PCR blood test, and you feel well. There are different levels of remission.

Treatments may include the following.

Chronic myeloid leukaemia (CML) is mainly treated with medicines called tyrosine kinase inhibitors, or TKIs.

In chronic myeloid leukaemia, chemotherapy means using anti-cancer drugs, also called cytotoxic drugs, to destroy or damage the leukaemia cells. The drugs work by disrupting the way these cells grow and divide.

Your doctors may suggest a stem cell transplant, which some people call a bone marrow transplant. It's an intensive treatment and isn't suitable for everyone. For chronic myeloid leukaemia (CML), it's not often used.

If other treatments haven't worked, some people with chronic myeloid leukaemia (CML) may be given interferon alpha while the disease is in the chronic phase.

Doctors may also use interferon alpha for people who need CML treatment and are planning to get pregnant, or are already pregnant.

Some CML treatments may affect your fertility or harm a developing baby. Because of this, you may be advised to use contraception to prevent a pregnancy.

If you're worried about your fertility, talk with your doctor before you start treatment.

Cancer support organisations have more information on cancer treatment options and on getting organised before cancer treatment.

If you're treated with a tyrosine kinase inhibitor (TKI) for chronic myeloid leukaemia (CML), your healthcare team will check on you every 1 to 2 weeks.

To start with, your doctor will do a polymerase chain reaction (PCR) blood test every 3 months to look for leukaemia cells. If you respond well to the TKI, this test may be done less often. Sometimes the doctor may also take a bone marrow sample, and they can tell you how often you might need that.

As time goes on, you may only need a check-up every 3 to 6 months.

If you have another type of treatment, your doctor or nurse will tell you how often your appointments will be. If you have any problems or notice new symptoms between appointments, tell your doctor or specialist nurse.

Most people with chronic myeloid leukaemia (CML) have a normal life expectancy. To help you stay as well as possible, you may want to change some things in your lifestyle. Even if you lived healthily before your diagnosis, you may want to make the most of your health.

A healthy lifestyle can help speed up your recovery. Even small changes may improve your well-being and your long-term health.

If you already live a healthy life, you may still choose to make some positive changes after treatment.

The charity Macmillan Cancer Support has more information on leading a healthy lifestyle after treatment.