A cancer in which large numbers of immature, or abnormal, white blood cells are produced by the bone marrow
Acute leukaemia is the most common childhood cancer. Until the 1960s, it was almost always fatal, but now most children survive because of better treatment.
In acute leukaemia, cancerous immature white blood cells multiply rapidly and accumulate in the bone marrow, disrupting the production of normal white blood cells, red blood cells, and platelets. A decrease in the number of normal white blood cells makes the body susceptible to infection. A deficiency of red blood cells leads to a reduction in the oxygen-carrying capacity of the blood (see Anaemia). A reduced number of platelets, which help to seal damaged blood vessels, may result in abnormal bleeding (see Thrombocytopenia).
There are two main types of acute leukaemia. In acute lymphoblastic leukaemia (ALL), the abnormal type of white blood cell involved is an immature lymphocyte (lymphoblast). In acute myeloid leukaemia (AML), the type of white blood cell that is abnormal is an immature myeloid cell (myeloblast).
ALL is the most common cancer in children; it occurs more often in boys. AML is more common in people over the age of 60, affecting men and women equally. Left untreated, acute leukaemia can be fatal within a few weeks.
In most cases of acute leukaemia, no cause can be identified. However, there are some factors that have been found to increase the risk of developing the disorder. For example, previous exposure to high levels of radiation, such as from radiotherapy, or exposure to some anticancer drugs (see Chemotherapy) may increase the future risk of acute leukaemia. Exposure to certain toxic chemicals, such as benzene in petrol, may also be a risk factor.
People who have myelodysplasia, which is a precancerous abnormality of the bone marrow, or those who have certain chromosomal abnormalities, such as Down’s syndrome, also have an increased risk of developing acute leukaemia.
The symptoms of acute leukaemia are caused by abnormal white blood cells overcrowding the bone marrow, which reduces the numbers of normal blood cells of all types. Symptoms are also caused by the invasion of abnormal blood cells into the bloodstream, where they multiply and spread easily to other organs and tissues in the body. The symptoms of acute leukaemia may develop rapidly and include:
Tiredness, pale skin, and shortness of breath on exertion due to anaemia.
Easy bruising and excessive bleeding, often from the gums.
Swelling in the neck, armpits, and groin due to enlarged lymph nodes.
Swelling of the abdomen due to an enlarged liver and spleen.
Since only immature, nonfunctioning white blood cells are produced, and the cancerous cells are abnormal, susceptibility to infections is increased.
Your doctor may arrange blood tests to look for abnormal white blood cells, low platelet levels, and reduced numbers of red blood cells. The diagnosis is confirmed by a bone marrow aspiration and biopsy, a procedure in which tissue samples are obtained for examination under a microscope. You may also need a lumbar puncture, in which a fluid sample is taken from around the spinal cord, to find out if the disease has spread to the nervous system.
If you have acute leukaemia, you will be admitted to hospital, where repeated courses of chemotherapy will be given to kill the abnormal cells in the bone marrow. The aim of this treatment is to induce a remission, a period of time during which the leukaemia is inactive.
A stem cell transplant may be offered if a suitable stem cell donor can be found. Before the procedure, you will be given chemotherapy and radiotherapy.
Acute leukaemia is curable, and the outlook for children is better than for adults. Most children treated for acute leukaemia make a full recovery. However, in adults, only about 1 in 3 under the age of 50 who is treated survives for longer than 5 years.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.