This information is about acute myeloid leukaemia (AML) in children. It is helpful to read it alongside our general information on children’s cancer, which contains more information about cancers in children, their diagnosis and treatment and the support services available.

One third of all childhood cancers are leukaemia, with approximately 400 new cases occurring each year in the UK. Less than a quarter of these are acute myeloid leukaemia (AML). AML can affect children of any age, and girls and boys are affected equally.

Leukaemia is a cancer of the white blood cells. All blood cells are produced in the bone marrow. Bone marrow is the spongy substance at the core of some of the bones in the body. Bone marrow contains:

• red blood cells that carry oxygen around the body
• white blood cells that help fight infection
• platelets that help the blood to clot and control bleeding.

There are two different types of white cell: lymphocytes and myeloid cells (including neutrophils). These white blood cells work together to fight infection. Normally white blood cells repair and reproduce themselves in an orderly and controlled way. In leukaemia, however, the process gets out of control and the cells continue to divide, but do not mature.

These immature dividing cells fill up the bone marrow and stop it from making healthy blood cells. As the leukaemic cells are immature, they cannot work properly. This leads to an increased risk of infection. Because the bone marrow cannot make enough healthy red blood cells and platelets, symptoms such as anaemia and bruising can occur.

There are four main types of leukaemia: acute lymphoblastic (ALL), acute myeloid (AML), chronic lymphocytic (CLL) and chronic myeloid (CML). Chronic leukaemias occur mostly in adults, and are extremely rare in children and young people. Each type of leukaemia has its own characteristics and treatment.

Acute myeloid leukaemia is an overproduction of immature myeloid white blood cells (blast cells).

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

There are different sub-types 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 sub-type of AML is important, as it helps the doctors to decide on the best treatment.

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

• M0 Acute myeloid leukaemia with minimal evidence of myeloid differentiation
• M1 Acute myeloblastic leukaemia without maturation
• M2 Acute myeloblastic leukaemia with maturation
• M3 Acute promyelocytic leukaemia (APL)
• M4 Acute myelomonocytic leukaemia
• M5 Acute monocytic/monoblastic leukaemia
• M6 Acute erythroleukaemia
• M7 Acute megakaryoblastic leukaemia

The exact cause of AML is unknown. Research is ongoing into possible causes of this disease. Children 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 AML, although this risk is still small. Other non-cancerous conditions, such as aplastic anaemia or the myelodysplastic syndromes, may increase a child’s risk of developing AML.

In recent years, there has been publicity about leukaemia occurring more often in children who live near nuclear power plants or high-voltage power lines. Research is being carried out to see if there is any definite link between these factors and leukaemia, but, at present, there is no evidence of this.

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

As the leukaemia cells multiply in the bone marrow, the production of normal blood cells is reduced. Children may therefore become tired and lethargic due to anaemia, which is caused by a lack of red blood cells. They may develop bruises, and bleeding may take longer to stop due to the low number of platelets present in their blood. Sometimes, children may suffer from infections because of low numbers of normal white blood cells.

A child 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.

A blood test usually shows low numbers of normal white blood cells and the abnormal leukaemic cells. A sample of bone marrow is needed to confirm the diagnosis.

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.

The aim of treatment for acute myeloid leukaemia is to destroy the leukaemia cells and enable the bone marrow to work normally again. Chemotherapy is the main treatment for AML. Usually a combination of chemotherapy drugs is given. The treatment usually has different phases.

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 still has leukaemia. When there is no evidence of leukaemia, the child's 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 leukaemic cells that may be left and to help to stop the AML from coming back. This treatment usually involves two or three more courses of chemotherapy.

Bone marrow transplantation Bone marrow transplantation is usually only used for children with AML that is likely to come back following standard chemotherapy, or for children whose leukaemia has come back (recurred) following standard treatment.

Central nervous system (CNS) treatment AML may sometimes develop in the brain and spinal cord. This can be prevented by injecting chemotherapy directly into the spinal fluid during a lumbar puncture (intrathecal chemotherapy). Intrathecal chemotherapy is usually given after each of the first two courses 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.

Many cancer treatments will cause side effects. This is because while the treatments are killing the cancer cells, they can also damage some normal cells. Some of the main side effects are:

• hair loss
• reduction in the number of blood cells produced by the bone marrow, which can cause anaemia, an increased risk of bruising, bleeding and infection
• loss of appetite and weight
• sickness (nausea) and vomiting.

Most side effects are temporary, and there are ways of reducing them and supporting your child through them. Your child’s doctor or nurse will talk to you about any side effects.

Late side effects

A small number of children may develop late side effects, sometimes many years later. These include possible problems with puberty and fertility, a change in the way their heart works, and a small increase in their risk of developing a second cancer in later life. Your child’s doctor or nurse will explain about any possible late side effects.

Many children have their treatment as part of a clinical research trial. Trials aim to improve our understanding of the best way to treat an illness (usually by comparing the standard treatment with a new or modified version of the standard treatment). Specialist doctors carry out trials for AML. Your child's medical team will talk to you about taking part in a clinical trial (if appropriate) and will answer any questions you may have. Written information is often provided to help explain things.

Taking part in a research trial is completely voluntary, and you'll be given plenty of time to decide if it is right for your child.

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

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

As a parent, the fact that your child has cancer is one of the worst situations you can be faced with. You may have many different emotions, such as fear, guilt, sadness, anger and uncertainty. These are all normal reactions, and are part of the process that many parents go through at such a difficult time.

Your child may have a range of powerful emotions throughout their experience of cancer. Our booklet, Peppermint Ward is a storybook for younger children with cancer. It looks at the issues that they and their family may face and helps them to explore their feelings. You can order the booklet online.

This section has been compiled using information from a number of reliable sources, including:

• Cancer in Children: Clinical Management (5th ed). Eds PA Voute et al. Oxford University Press, 2005.

For further references, please see the general bibliography.