A group of bone marrow cancers in which abnormal white blood cells multiply uncontrollably
In leukaemia, cancerous white blood cells multiply rapidly and accumulate within the bone marrow, where all types of blood cell are normally produced. This reduces the production of normal white blood cells, red blood cells, and platelets within the bone marrow.
A reduction in the number of red blood cells reduces the oxygen-carrying capacity of blood (see Anaemia). If levels of normal white blood cells are lowered, infection becomes a risk, while reduced levels of platelets may result in abnormal bleeding (see Thrombocytopenia). In most leukaemias, the cancerous white blood cells spread via the blood, causing the lymph nodes, liver, and spleen to enlarge.
The two main types of leukaemia are acute leukaemia, in which the symptoms develop rapidly, and chronic leukaemia, in which the symptoms can take years to develop. Adults may develop either type of leukaemia, but children usually have the acute form. Acute leukaemia can be divided into acute lymphoblastic and acute myeloid leukaemia, depending on the type of white blood cell involved. Chronic leukaemia also takes two forms: chronic lymphocytic leukaemia and chronic myeloid leukaemia.
All leukaemias produce the usual symptoms of anaemia: tiredness, pale skin, and shortness of breath on mild exertion. Other symptoms may include weight loss, fever, night sweats, excessive bleeding, and recurrent infections.
Leukaemia may be diagnosed from a blood test and a bone marrow aspiration and biopsy. The treatment usually involves chemotherapy and, in some cases, radiotherapy. Blood transfusions may also sometimes be necessary.
The outlook varies depending on the type of leukaemia and its severity. Treatment of leukaemia is more likely to be successful in children.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.