Acute myeloid leukaemia

This page was written by the Children's Cancer and Leukaemia Group (CCLG).

Acute myeloid leukaemia (AML) is a type of blood cancer and can affect children and young people of any age. Approximately, 25% of childhood leukaemia cases are acute myeloid (AML).

Leukaemia is a cancer of the white blood cells, which help fight infection in the body. Normally, white cells develop, repair and reproduce themselves in an orderly and controlled way but in leukaemia cells, the process gets out of control.

AML is a cancer where too many immature myeloid white blood cells (blast cells) are made by the body.

Cells that have started to show some of the features of myeloid cells are said to show ‘differentiation’. Cells that do not show signs of becoming a particular type of white blood cell are known as undifferentiated.

There are different subtypes of AML, depending upon exactly which type of cell has become leukaemic, the stage of development (maturation) the cells are at and whether the cells are differentiated. Knowing the subtype of AML is important, as it helps doctors decide on the best treatment.

There are several classification systems for the subtypes of AML. The most commonly used system in the UK is the French-American-British (FAB) system.

FAB classification of AML

M0 – AML with minimal evidence of myeloid differentiation
M1 – AML without maturation
M2 – AML with maturation
M3 – Acute promyelocytic leukaemia (APL)
M4 – Acute myelomonocytic leukaemia
M5 – Acute monocytic/monoblastic leukaemia
M6 – Acute erythroleukaemia
M7 – Acute megakaryoblastic leukaemia
A system known as the WHO (World Health Organisation) classification system is also sometimes used.

Causes

The exact cause of AML is unknown. Research into possible causes of this disease is ongoing. Children and young people with certain genetic disorders, such as Down’s syndrome or Li-Fraumeni syndrome, are known to have a higher risk of developing leukaemia. Brothers and sisters of a child with AML have a slightly increased risk of developing it, although this risk is still small. Other non-cancerous conditions, such as aplastic anaemia or the myelodysplastic syndromes (MDS), may increase a child’s risk of developing AML.

AML, like all types of cancer, is not infectious and cannot be passed on to other people.

Signs and symptoms

As the leukaemia cells multiply in the bone marrow, the production of normal blood cells is reduced. Children and young people may therefore become:

  • tired and lethargic because of anaemia, which is caused by a lack of red blood cells
  • pale skin
  • develop bruises
  • unusual bleeding which may take longer to stop because of the low number of platelets present in their blood (which help blood to clot)
  • children can suffer from frequent infections because of low numbers of normal white blood cells
  • purple skin rash called petechiae.

A child or young person is likely to feel generally unwell and may complain of aches and pains in the limbs or may have swollen lymph glands.

At first, the symptoms are just like those of a viral infection, but when they continue for more than a week or two, the diagnosis usually becomes clear.

How AML is diagnosed

A blood test usually shows low numbers of normal white blood cells and the presence of the abnormal leukaemia cells. A sample of bone marrow is usually needed to confirm the diagnosis. The bone marrow sample is also examined to check for any abnormalities in the chromosomes and for a test called MRD (minimal residual disease).

A test called a lumbar puncture is done to see if the spinal fluid contains any leukaemia cells. A chest x-ray is also done, which will show if there are any enlarged glands in the chest. Other tests may be necessary, depending on your child’s symptoms.

These tests will help to identify the precise type of leukaemia and help doctors decide on the best treatment.

Treatment

The aim of treatment for AML is to destroy the leukaemia cells and enable the bone marrow to work normally again. Chemotherapy is the main treatment for AML and is given according to a treatment plan (often called a protocol or regimen).

The treatment is given in several phases, or ‘blocks’, which are explained below.

Induction

This phase involves intensive treatment, aimed at destroying as many leukaemia cells as possible. It usually involves two courses (cycles) of a combination of chemotherapy drugs.

A bone marrow test is taken at the end of induction treatment to confirm whether or not the child or young person still has leukaemia. When there is no evidence of leukaemia, the condition is referred to as being in remission.

Post-remission treatment

When there are no signs of the leukaemia in the blood or bone marrow, further treatment is often given. This phase of the treatment aims to destroy any leukaemia cells that may be left and to help stop the AML from coming back. This treatment usually involves two more courses of chemotherapy.

Bone marrow transplant

This treatment is usually only used for children or young people with AML that is likely to come back or has come back (recurred) following standard chemotherapy.

Central nervous system (CNS) treatment

AML may sometimes develop in the brain and spinal cord. This can be prevented by injecting chemotherapy drugs directly into the spinal fluid during a lumbar puncture (intrathecal chemotherapy). Intrathecal chemotherapy is usually given with the lumbar puncture performed at the time of diagnosis and before the second course of chemotherapy. Sometimes a more intensive treatment is needed, and the intrathecal drugs are given more frequently until all the regular chemotherapy has been completed. Occasionally, radiotherapy to the brain is also necessary.

Follow-up care

Many children and young people with AML are cured. If the leukaemia comes back after initial treatment, it usually does so within the first three years. Most with AML grow and develop normally.

If you have specific concerns about the condition and treatment, it’s best to discuss them with your doctor, who knows the situation in detail.

 

This information was written by the Children’s Cancer and Leukaemia Group (CCLG)

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