What is leukaemia?

Leukaemia is a form of cancer affecting the white blood cells. Blood cells include white cells to fight infection, red cells to carry oxygen and platelets which help stop bruising and bleeding. Blood cells are made in the bone marrow and when mature they are released into the peripheral blood. However, in leukaemia, these early cells fail to mature and multiply in an uncontrolled way, spilling out into the circulation. They also crowd out normal cells in the bone marrow effectively preventing normal blood cell production. This causes the symptoms of leukaemia which are anaemia, reduced resistance to infection and abnormal bleeding. It can also cause bony pain. This process usually happens very quickly and symptoms develop rapidly over a few days or weeks. Rapid development of leukaemia symptoms is called ‘acute’ leukaemia. The type of leukaemia: ‘lymphoblastic’ or ‘myeloblastic’ (myeloid) depends on what type of abnormal cell is found on testing.

Without treatment acute leukaemia can cause death in a few weeks from bone marrow failure. Treatment takes from 9 months to 2-3 years to complete depending on the type of leukaemia

There are two main types of acute leukaemia in children -:

• Acute lymphoblastic leukaemia (ALL)
• Acute myeloblastic (myeloid) leukaemia (AML)

ALL is the most common leukaemia accounting for 80% of cases, the remaining 20% being AML. ALL is also the most common childhood cancer. Children with Down syndrome are more likely to develop leukaemia. Other genetic conditions associated with leukaemia include neurofibromatosis, Shwachman Syndrome, Bloom Syndrome and ataxic telangiectasia.

Survival rates

Survival rates for acute myeloblastic (myeloid) leukaemia (AML) have significantly improved but are less good than those for acute lymphoblastic leukaemia (ALL) at around 65% at 5 years. Induction chemotherapy treatment for AML will put around 90% of children in to remission. Of those children who do not go in to remission about half will die as a result of the disease or its treatment during induction therapy and the other half will have poor prognosis resistant disease. AML is fatal without treatment. The treatment is necessarily aggressive and causes severe bone marrow suppression. Infection related to bone marrow suppression is the main cause of complications and death in this condition. A subtype of AML - promyelocytic AML or acute promyelocyctic leukaemia (APL) has a much better survival rate at around 80% but an increased risk of death from bleeding at presentation.

What is the incidence of leukaemia?

Around one third of all childhood cancers are leukaemias. Of these, 80% are the Acute Lymphoblastic (ALL) type. ALL is more common in areas of Britain with higher socio-economic status than average. Acute myeloblastic (myeloid) leukaemia is much less common and chronic forms of myeloid leukaemia are very rare.

Note: - chronic myeloid leukaemia is not covered by this guidance.

Leukaemia is more common in boys than girls. There is a sharp peak in incidence at age 2-3 years. 400 to 500 children develop a type of leukaemia each year in the UK. More than half of these will be aged under 5 at the time of diagnosis.