Chronic myeloid leukaemia

The bone marrow is the soft spongy material in the centre of bones. The bone marrow makes early stage cells called stem cells, from which all other blood cells develop.

There are two types of stem cells:

• Myeloid stem cells develop into three types of blood cells: red, white and platelets.
• Lymphoid stem cells develop into other types of white blood cells called T-lymphocytes and B-lymphocytes.

When stem cells mature, they are released into the bloodstream.

The blood

Blood is pumped around your body to provide oxygen, nutrients, fight infections and remove waste products. The three main types of blood cells are carried along in a clear fluid called plasma.

• Red blood cells: Carry oxygen from your lungs to the rest of your body. If you don’t have enough red cells, you may be pale and tire easily because your body is not getting enough oxygen. A shortage of red blood cells is called anaemia.
• White blood cells: Fight infections. If you do not have enough white cells, your risk of infection increases.
• Platelets: Help your blood clot and stop bleeding. If you do not have enough platelets, you may bruise for no known reason, have frequent nose bleeds or prolonged bleeding, or develop a rash of small dots to the arms, legs or body.

What is chronic leukaemia?

Chronic leukaemia develops when your white blood cells grow out of control. The abnormal white cells live too long, so there are too many circulating in the blood. These white cells are not fully developed and do not work properly.

The bone marrow becomes crowded with abnormal white cells, leaving little room for healthy red cells and platelets to be produced.

Types of chronic leukaemia

There are two types of chronic leukaemia depending on what type of white blood cell is involved:

• chronic myeloid leukaemia (CML)
• chronic lymphocytic leukaemia (CLL).

CML affects the granulocytes. They are part of the myeloid family of white blood cells.

How common is it?

In 2003 in NSW, 44% of the 883 new cases of leukaemia were chronic leukaemia.

CML can occur at any age, but is more common after 60. It is rare in children.

Most people diagnosed with CML have an abnormal chromosome called the Philadelphia chromosome. Chromosomes contain genes, which are the full set of instructions for growth and development.

CML, like other forms of leukaemia, does not run in families.

CML has also been linked to exposure to high levels of radiation, such as being a survivor of an atomic bomb explosion.

Many people with chronic myeloid leukaemia have no symptoms. The illness is difficult to detect in the early stages because the symptoms tend to be mild at first and get worse slowly.

Symptoms of CML include:

• tiredness
• weight loss
• sweating
• lump in the left side of the stomach from an enlarged spleen
• swollen lymph glands
• bruising or bleeding from a low platelet count.

Occasionally, a person will have none of these symptoms and the leukaemia is discovered during a routine blood test.

This test is usually done to confirm if leukaemia cells are present and to work out which leukaemia you have.

The bone marrow sample is examined for cell and chromosome changes, which in leukaemia cells are different to the normal cells. These changes also influence the type of treatment your doctor recommends for you.

A thin needle is used to remove a small piece of bone and bone marrow fluid from the hipbone.

A bone marrow biopsy is an uncomfortable procedure and can be painful. You will be given a local anaesthetic to numb the area. The procedure usually lasts up to 30 minutes. There are a wide range of pain relief medications available. Ask you doctor what is suitable for you before the biopsy. You may be asked to fast (not eat or drink) prior to the procedure. If you have sedation for the procedure this will make you drowsy so you will need someone to drive you home.

Most people diagnosed with CML have an abnormal chromosome called the Philadelphia chromosome.

The Philadelphia chromosome carries an abnormal DNA code that instructs the leukaemia cells. This protein acts as a signal, telling the leukemic cells to grow and multiple.

These tests are done on blood or bone marrow cells to look for changes in your chromosomes and their contents.

Some people with CML may need a CT (computerised tomography) scan.

This test uses x-ray beams to take pictures of the inside of your body. It can see if the lymph nodes are affected and if your spleen is enlarged.

A CT scan takes about 30 minutes.

Before the scan, a special dye may be injected into a vein, probably in your arm. This will make the pictures the scan takes clearer. For a few minutes, this may make you feel hot all over.

You will lie flat on a table while the CT scanner, which is large and round like a doughnut, takes pictures. Most people are able to go home as soon as their scan is done.

The results of these tests will be used to see how far your leukaemia has spread. This is called staging.

The staging of CML is described in three phases.

• Chronic: A few blast cells are found in the blood and bone marrow. This stage usually lasts a few years.
• Accelerated: After several years, the leukaemia may suddenly change and grow quicker. Symptoms include enlarged spleen, rising white cell count and high temperature.
• Blast: The number of blast cells increases, causing symptoms to worsen. Blast cells often spread to other organs.

Prognosis means the expected outcome of a disease.

You need to discuss the prognosis of your chronic leukaemia with your doctor. Only someone who knows your medical condition can tell you what to expect and the treatment options that are best for you.

CML can be cured with bone marrow transplantation and possibly with newer drugs, such as imatinib. Treatment becomes less effective as the disease progresses through the three phases. Relapse during the accelerated phase makes control more difficult.

Your GP will arrange the initial blood test to check out your symptoms. If leukaemia is suspected, you will be referred to other health professionals, including:

• Haematologist: diagnoses and treats diseases of the bone marrow, blood and lymphatic system
• Radiation oncologist: prescribes and co-ordinates the course of radiotherapy
• Nurses: support and assist you through all stages of your treatment
• Other health professionals that you may also see include:
• Dietician: recommends the best eating plan to follow while you are in treatment and recovery
• Social worker, physiotherapist and occupational therapist: link you to support services and help you to resume your normal activities.

Imatinib, also called Glivec, is used to treat CML.

Imatinib blocks the action of a protein produced by the Philadelphia chromosome. The cancer cells cannot grow without this protein.

This drug can bring on remission in chronic phase CML. Imatinib is less successful at treating the accelerated phase of CML because the cancer cells don’t respond to the drug.

Imatinib is taken as tablets.

Side effects
Most people get side effects but they are usually mild and can be managed.

They include feeling sick, swelling of the face, especially around the eyes, diarrhoea, rash and low blood counts.

Biological therapy, which includes immunotherapy, uses materials made by the body’s immune system or materials made in a laboratory to stimulate the body to fight infection.

Immunotherapy for chronic myeloid leukaemia includes a protein called gamma interferon, which is made by the white blood cells.

Another type of immunotherapy is antibodies. Antibodies work by finding and becoming attached to targeted cells such as lymphocytes and then destroying them.

Monoclonal antibodies, which are made in the laboratory, can be given intravenously.

Side effects
Flu-like symptoms, such as chills, fevers, muscle aches and tiredness.

Bone marrow transplantation involves very high doses of chemotherapy. The chemotherapy will destroy the bone marrow but transplanted stem cells restore blood cell numbers to normal.

Stem cells are early-stage cells from which other cells develop.

Sources of stem cells

• Bone marrow
• Blood – these are called peripheral stem cells

Donors of stem cells

• There are two types of bone marrow transplantation:
• from another person: allogeneic transplant
• your own autologous transplant

Chemotherapy uses drugs, called cytotoxic, to kill or slow the growth of leukaemia cells. These are called cytotoxic drugs.

The commonly used drug is hydroxyurea, which is taken by mouth.