Encyclopaedia


Leukaemia, chronic myeloid

Introduction

Leukaemia is cancer of the white blood cells. Symptoms of leukaemia include:

  • pale skin
  • tiredness
  • breathlessness
  • repeated infections over a short space of time

Chronic leukaemia means that the condition progresses slowly over the course of many years and no immediate treatment is required.

These pages focus on chronic myeloid leukaemia (see Types of chronic leukaemia below).

Bone marrow

All of the blood cells in your body are produced by bone marrow. Bone marrow is a spongy material found inside the bones. It is important because it produces special cells called stem cells.

Stem cells are very useful because they have the ability to create other specialised cells that carry out important functions. The stem cells in bone marrow produce three important types of blood cells:

  • red blood cells, which carry oxygen around the body
  • white blood cells, which help fight infection
  • platelets, which help stop bleeding

In leukaemia, the cancer begins in the stem cells and causes them to produce more white blood cells than are needed. Over time, the cancerous white blood cells build up, disrupting the normal balance of cells in the blood.

This means that the body does not have enough red blood cells or platelets. This can cause symptoms of anaemia, such as tiredness, as well as increasing the likelihood of excessive bleeding.

Also, as the white blood cells are not properly formed, they are less effective at fighting bacteria and viruses, making you more vulnerable to infection.

Types of chronic leukaemia

Chronic leukaemia is classified according to the type of white blood cells that are affected by cancer. There are two main types of white blood cell:

  • lymphocytes - which are mostly used to fight viral infections
  • myeloid cells - which perform a number of different functions, such as fighting bacterial infections, defending the body against parasites and preventing the spread of tissue damage 

There are two main types of acute leukaemia that are related to the two main types of white blood cells. They are:

  • chronic lymphocytic leukaemia - which is cancer of the lymphocytes
  • chronic myeloid leukaemia - which is cancer of the myeloid cells

These pages focus on chronic myeloid leukaemia (CML). For information on chronic lymphocytic leukaemia, go to the A-Z topic on chronic lymphocytic leukaemia

How common is chronic myeloid leukaemia?

Chronic leukaemia is an uncommon type of cancer. Each year, in England and Wales, an estimated 600 new cases of CML are diagnosed.

CML is more common in people aged 40-60. There is no evidence that it runs in families.

Chronic leukaemia can be cured using a bone marrow transplant. However, this is not suitable for everyone.

Outlook

The outlook for CML depends to a large extent on how well a person responds to treatment with a new type of medication called imatinib. For people who respond well, the outlook is good, and it has been estimated that they may live up to 20 years after a receiving a diagnosis.

The use of imatinib only became widespread after 2001, so information about how it affects long-term survival rates in people with CML is unavailable.

Unfortunately, some people do not respond to imatinib, and an estimated 35% of them will live for five years or more after their diagnosis.

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Symptoms

There are three stages of chronic myeloid leukaemia (CML), which are outlined below.

  • Chronic – the number of cancerous blood cells in your blood remains low and there are very mild or no symptoms.
  • Accelerated – the number of cancerous blood cells in your blood begins to increase at a faster rate, your symptoms will gradually get worse and you will be more vulnerable to infection.
  • Advanced – the number of cancerous blood cells in your blood is dangerously high, symptoms will be severe and you will be very vulnerable to infection. The advanced stage of CML is also known as a blast crisis.

The symptoms of CML during the condition’s chronic or accelerated stage include:

  • tiredness
  • loss of appetite
  • weight loss
  • increased sweating
  • abnormal bruising and bleeding
  • night sweats

CML can also cause swelling in your spleen (an organ that helps to filter impurities from your blood). This can cause a lump to appear on the left side of your abdomen, which may be painful when touched. A swollen spleen can also put pressure on your stomach, causing a lack of appetite and indigestion.

The symptoms of CML in its advanced stage will be much more noticeable and troublesome. They include:

  • repeated infections in a short space of time, due to the lack of healthy white blood cells
  • unusually pale skin, due to the lack of red blood cells
  • bleeding, such as nose bleeds, bleeding gums, or unusually heavy periods (in women), due to the lack of platelets (blood-clotting cells)
  • easily bruised skin
  • swollen lymph nodes (glands)
  • itchy skin
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Causes

Genetic mutation

Chronic leukaemia begins with an alteration to the structure of the DNA found in the stem cells that are responsible for producing white blood cells. The DNA provides the cells with a basic set of instructions, such as when to grow and reproduce. The alteration that occurs to the DNA’s structure is known as a genetic mutation.

The mutation in the DNA changes the instructions which causes the stem cells to produce more white blood cells than are needed. The white blood cells are also produced too quickly and, over time, they begin to lose their infection-fighting properties.

Eventually, the increase in the number of affected white blood cells will lead to a corresponding decrease in red blood and platelets. The reduction in the other blood cells is an underlying cause for many of the symptoms of chronic leukaemia.

Possible triggers for chronic leukaemia

What triggers the development of chronic leukaemia and causes the initial mutation in stem cells is unknown. The one proven risk factor is exposure to radiation.

However, radiation is only a significant risk if the levels are extremely high, such as those recorded after an atomic bomb explodes, or those released after a nuclear reactor accident, such as the one at Chernobyl.

Benzene

There is limited evidence that prolonged exposure to the chemical benzene leads to an increased risk of chronic myeloid leukaemia (CML). Benzene is found in petrol and is also used in the rubber industry, but there are strict controls to protect people from prolonged exposure.

Benzene is also found in cigarettes. However, it is thought that smoking is more of a risk factor in acute leukaemia than it is in chronic leukaemia.

Occupational risks

There are a number of occupations that have been linked to an increase risk of chronic leukaemia, possibly due to exposure to certain substances such as pesticides or chemicals.

These occupations include:

  • all types of agricultural workers
  • people who are involved with rubber or plastic manufacture
  • tailors and dressmakers
  • cleaners
  • builder’s labourers
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Diagnosis

Blood tests

Suspected cases of chronic leukaemia are usually first detected after a blood test, which has often been carried to diagnose another, unrelated condition.

A blood test that reveals abnormally high levels of white blood cells could be a sign of chronic leukaemia. If you have a blood test with abnormal results, you will be referred to a haematologist (a specialist in treating blood conditions) for further testing.

Bone marrow biopsy

To confirm a diagnosis of chronic leukaemia, the haematologist will take a small sample of your bone marrow to examine under a microscope. This procedure is known as a bone marrow biopsy. A bone marrow biopsy is usually carried out under a local anaesthetic.

The haematologist will numb an area of skin at the back of your hip bone, before using a needle to remove the bone marrow sample. The procedure is usually painless although you may experience some bruising and discomfort for a few days afterwards. The procedure takes around 15 minutes to complete and you should not have to stay in hospital overnight.

The bone marrow sample will be checked to see if there are cancerous cells. If there are, the biopsy will also be able to help determine which type of chronic leukaemia is present.

Further tests

There are a number of additional tests that can be used to help reveal more information about the progress and extent of the leukaemia, which can also provide an important insight into how the leukaemia should be treated. These are outlined below.

Cytogenetic testing

Cytogenetic testing involves identifying the genetic make-up of the cancerous cells. There are a number of specific genetic variations that can occur during leukaemia and knowing what these variations are can have an important impact on treatment.

For example, 90% of people with chronic myeloid leukaemia (CML) have an altered gene, known as the Philadelphia chromosome. People who have this altered gene are known to respond well to a medicine called imatinib.

Lymph node biopsy

If you have been diagnosed with chronic leukaemia, further biopsies may be carried out on any enlarged lymph nodes that you have. These are to see how far the leukaemia has spread.

CT scans

If you have chronic leukaemia, a computerised tomography (CT) scan may be used to check that your other organs, such as your heart and lungs, are healthy.

See the A-Z topic about CT scans for more information.

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Treatment

Your treatment plan

As chronic leukaemia is a complex condition, it is usually treated by a team of different healthcare specialists working together. This type of team is known as a multidisciplinary team (MDTs).

Members of your MDT may include:

  • a haemato-oncologist (a specialist in the non-surgical treatment of leukaemia using techniques such as chemotherapy)
  • a haemato-pathologist (a specialist in the study of cancerous blood cells)
  • a pharmacist
  • a social worker
  • a psychologist
  • a specialist cancer nurse (who will serve as the first point of contact between you and the other members of the MDT)
  • a counsellor

There are several factors that will need to be taken into account when deciding on your treatment. They include:

  • your age
  • the extent of your cancer
  • the likely progression of your cancer
  • the possible side effects of treatment

No one will rush you into making a decision about your treatment, and you are free to talk to as many people as you want to, including your partner, family and friends.

Many people find that it can be helpful to write a list of questions at home to ask the MDT. Your MDT will be able to recommend what they feel are the best treatment options for you, but ultimately the decision will be yours.

The treatment of chronic leukaemia when the condition is in its early stages will depend on what type of chronic leukaemia you have. However, the treatments for both chronic myeloid leukaemia (CML) and chronic lymphocytic leukaemia in their advanced stage are more or less the same.

Early-stage chronic myeloid leukaemia (CML)

Imatinib

A medicine called imatinib is the main treatment that is recommended for CML. It is usually given as soon as a diagnosis is made because the medicine is designed to slow the progression of CML, and to prevent the condition reaching the accelerated or advanced phase.

Imatinib is a type of tyrosine kinase inhibitor. This means that it blocks a protein called tyrosine kinase (tyrosine kinase helps to stimulate the growth of cancer cells). This reduces the production of abnormal white blood cells.

Imatinib is taken orally (as a tablet). The side effects of imatinib are usually mild and should improve with time. They include:

  • nausea
  • vomiting
  • swelling in the face and lower legs
  • muscle cramps
  • rash
  • diarrhoea

Alternatives to imatinib

It is estimated that 10-40% of people who take imatinib become resistant to its effects, so an alternative treatment is required. Two new medications that can be used as an alternative to imatinib are:

  • nilotinib
  • dasatinib

Both medications work in a similar way to imatinib in that they block the effects of proteins that help stimulate the growth of cancer cells.

Side effects of nilotinib include:

  • vomiting
  • abdominal pain
  • bone and joint pain
  • dry skin
  • loss of appetite
  • hair loss
  • insomnia
  • night sweats
  • dizziness
  • tingling or numbness

Common side effects of dasatinib include:

  • diarrhoea
  • headache
  • a rash or red, dry, itchy skin
  • a build-up of fluids in the body, such as around your legs or face
  • fatigue
  • breathlessness
  • nausea
  • bone and muscle pain

If the side effects become particularly troublesome, temporarily stopping the treatment usually helps to bring them under control. Treatment can then be resumed, possibly using a lower dose of medication. 

Dasatinib can also lead to a sudden drop in the number of blood cells, which means that you will become vulnerable to infection and you will bruise and bleed more easily.

See Chronic leukaemia – Complications for more information and advice about being more vulnerable to infection and bleeding.

The National Institute for Health and Clinical Excellence (NICE) has not yet made a decision about whether the NHS should provide treatment with nilotinib and dasatinib for people with chronic leukaemia.

Whether or not you will be offered dasatinib or nilotinib will be at the discretion of your Health Board. If you decide to pay for the medication privately, the cost of a 30-day course of dasatinib or nilotinib is around £2,500. Your Health Board may choose to fund some of this cost, but again, the decision is entirely at their discretion and they have no legal obligation to do so.

Alternatively, you may be offered nilotinib and dasatinib by taking part in a clinical trial. For more information about clinical trials, see below.

Clinical trials

In the UK, a number of clinical trials are underway that aim to find the best way to treat chronic leukaemia. Clinical trials are studies that use new and experimental techniques to see how well they work in treating and possibly curing chronic leukaemia.

However, you should be aware that there is no guarantee that the techniques that are being studied in the clinical trial will be more effective than current treatments.

Your care team will be able to let you know whether there are any clinical trials available in your area, as well as explaining the benefits and risks involved.

Interferon alpha

Around 30% of people with CML fail to respond to treatment to the medications that are discussed above. In this case, an alternative medication called interferon alpha may be recommended.

Interferon alpha may also be recommended if you find that the side effects of imatinib, nilotinib or dasatinib are particularly unpleasant.

Interferon alpha works by encouraging your immune system to attack the cancerous cells. It is given by injection, using a syringe. You or a relative can be trained to use the syringe so that you can have the injection at home.

The most common side effects of interferon alpha are flu-like symptoms, such as fever, chills, and muscle and joint pain. The side effects usually begin three hours after an injection and resolve after a few hours.

The side effects of interferon alpha should improve over time, but if they become troublesome, inform your MDT because additional medicines are available that can help prevent the side effects.

Less common side effects of interferon alpha include:

  • nausea
  • vomiting
  • mood changes, such as depression
  • hair loss
  • dizziness
  • "pins and needles" in your hands and feet
  • infertility

The menstrual cycle of women who are using interferon alpha may be interrupted, and men may experience a decrease in their sperm count. For most people, infertility will be temporary, although it can be permanent in a minority of cases.

You should inform your MDT if you experience any of the less common side effects listed above because your dosage may need to be reviewed.

Treating advanced chronic myeloid leukaemia

Chemotherapy

Once chronic myeloid leukaemia has progressed to a more advanced stage, chemotherapy is the next treatment.

Chemotherapy tablets are usually used first because they have fewer and milder side effects than chemotherapy injections. Side effects include:

  • tiredness
  • skin rash
  • increased vulnerability to infection

Chemotherapy can weaken your immune system, which helps protect you against infection. This is known as being immunocompromised. See Chronic leukaemia – Complications for more information about this.

If your symptoms persist or get worse, chemotherapy injections (intravenous chemotherapy) will need to be used. Intravenous chemotherapy causes more side effects than chemotherapy tablets and they tend to be more severe.

Side effects include:

  • nausea
  • vomiting
  • tiredness
  • hair loss
  • infertility

These side effects should resolve after your treatment has finished, although there is a risk that infertility could be permanent. See Chronic leukaemia – Complications for more information about possible infertility treatments.

Rituximab

Rituximab is a new type of medication that is increasingly being used in combination with chemotherapy to treat CLL. Rituximab is what is known as a monoclonal antibody.

Monoclonal antibodies are antibodies that are genetically engineered in a laboratory. They are designed to directly target and attack cancer cells. This is why monoclonal antibody therapy can be referred to as targeted therapy.

Rituximab works by targeting a protein that is found on the surface of cancer cells, and encouraging your immune system to attack the protein which, in turn, should kill the cancer cells.

Rituximab is administered directly into your vein over the course of several hours. This is known as an infusion.

Common side effects of rituximab include:

  • flu-like symptoms, such as chills and a high temperature, while the medication is being given
  • dizziness
  • nausea
  • vomiting

In rare cases, rituximab can cause severe allergic reactions in some people. This is known as an infusion reaction and it can be fatal if left untreated.

Most infusion reactions occur within 24 hours of the first time that someone begins treatment. Therefore, it is likely that you will be closely monitored once your treatment begins. If you start to experience the symptoms of an infusion reaction, such as shortness of breath or chest pain, anti-allergy medicines, such as corticosteroids, can be used to help relieve your symptoms.

Bone marrow and stem cell transplants

The only available cure for chronic leukaemia is to have a bone marrow or stem cell transplant.

Before transplantation can take place, the person receiving the transplant has to have aggressive, high-dose chemotherapy and radiotherapy in order to destroy any cancerous cells in their body.

This can put enormous strain on the body and can cause significant side effects and potential complications. Transplantations have better outcomes if the donor has the same tissue type as the person who is receiving the donation. The best candidate to provide a donation is usually a brother or sister with the same tissue type.

Due to these issues, transplantations are usually only successful when they are carried out in children and young people, or older people in good health, and there is a suitable brother or sister who can provide a donation.

In most cases of chronic leukaemia, the potential risks of transplantation far outweigh any benefit. For example, the chances of an elderly person with advanced chronic leukaemia surviving a bone marrow transplant can be as low as one in five.

However, you may have specific individual circumstances that mean that the benefits of treatment do outweigh the risks.

See the A-Z topic about Bone marrow transplant for more on bone marrow and stem cell transplantation.

Deciding against treatment

As many of the treatments that are described in this section have unpleasant side effects that can affect your quality of life, you may decide against having a particular type of treatment.

This is entirely your decision and your MDT will respect any decision that you make. Pain relief and nursing care will be made available as and when you need it. 

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Complications

Immunocompromised

Being immunocompromised (having a weakened immune system) is a common complication of chronic leukaemia. There are two reasons for this:

  • The lack of healthy white blood cells means that your immune system is less able to fight infection.
  • Many of the medicines used to treat chronic leukaemia can weaken the immune system.

This means that you are more vulnerable to developing an infection, and that any infection you have has an increased potential to cause serious complications.

You may be advised to take regular doses of antibiotics to prevent infections occurring. You should immediately report any possible symptoms of an infection to your GP or care team because prompt treatment may be required to prevent serious complications.

Symptoms of infection include:

  • high temperature (fever) of 38C (101.4F) or above
  • headache
  • aching muscles
  • diarrhoea
  • tiredness

Avoid contact with anyone who is known to have an infection, even if it is a type of infection that you were previously immune to, such as chickenpox or measles. This is because your previous immunity to these conditions will probably be suppressed (lowered).

While it is important to go outside on a regular basis, both for exercise and for your psychological wellbeing, avoid visiting crowded places and using public transport during rush hour.

Also ensure that all of your vaccinations are up-to-date. Your GP or care team will be able to advise you about this. You will be unable to have any vaccine that contains activated particles of viruses of bacteria such as:

  • the mumps, measles and rubella (MMR) vaccine
  • the polio vaccine
  • the oral typhoid vaccine
  • the BCG vaccine (used to vaccinate against tuberculosis)
  • the yellow fever vaccine

Infertility

Many treatments used to treat chronic leukaemia can cause infertility. In some cases, infertility may be permanent.

Your multidisciplinary team will be able to provide a good estimation of the risk of infertility in your specific circumstance.

It may be possible to take steps to guard against any risk of infertility before beginning treatment. Men can have samples of their sperm stored so that it can be used to implant an embryo. Similarly, women can have fertilised embryos stored, which can then be placed back into the womb after treatment.

For more information see the A-Z topic on infertility.

Psychological effects of chronic leukaemia

Receiving a diagnosis of chronic leukaemia can be very distressing, particularly if it is unlikely that your condition can be cured. At first, the news may be difficult to take in.

The situation can be made worse if you are confronted with the knowledge that even though your leukaemia may not currently be causing any symptoms, it could be a serious problem in later life. Having to wait many years to see how the leukaemia develops can be immensely stressful and can trigger feelings of anxiety and depression.

If you have been diagnosed with leukaemia, talking to a counsellor or psychiatrist (a doctor who specialises in treating mental health conditions) may help you to combat feelings of depression and anxiety. Antidepressants or medicines that help to reduce feelings of anxiety may also help you cope better with the condition.

You may find it useful to talk to other people who are living with leukaemia. Your GP or multidisciplinary team may be able to provide you with details of local support groups.

Another excellent resource is Macmillan Cancer Support. Their helpline number is 0808 808 00 00 and is open Monday to Friday, 9am–8pm.  

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The information on this page has been adapted by NHS Wales from original content supplied by NHS Choices.

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