What is leukaemia?
Leukaemia is the general name given to a group of cancers that develop in the bone marrow. Leukaemia originates in developing blood cells that have undergone a malignant change. This means that they multiply in an uncontrolled way and do not mature properly, leaving them unable to function as they should.
Most cases of leukaemia originate in developing white cells. In a small number of cases leukaemia develops in other blood-forming cells, for example in developing red cells or developing platelets. Leukaemia can also be either myeloid or lymphocytic. The terms myeloid and lymphocytic refer to the types of cells in which the leukaemia first started. Myeloid stem cells develop into red cells, white cells (neutrophils, eosinophils, basophils and monocytes) and platelets. Lymphoid stem cells develop in two other types of white cells called T-lymphocytes and B-lymphocytes.
Both adults and children can develop leukaemia but certain types are more common in different age groups.
Types of leukaemia
There are several different types and subtypes of leukaemia. Leukaemia can be either acute or chronic.
Under normal conditions the bone marrow contains a small number of immature cells, called blast cells. These immature blast cells develop into mature white cells, red cells and platelets which are eventually released into the blood stream.
In people with acute leukaemia, the diseased bone marrow produces an excessive number of abnormal blast cells, called leukaemic cells. These cells accumulate in the bone marrow interfering with the production of normal blood cells. Acute leukaemia develops and progresses quickly and therefore needs to be treated as soon as it is diagnosed.
Common forms of acute leukaemia are:
» Acute myeloid leukaemia (AML)
» Acute lymphoblastic leukaemia (ALL)
» Acute promyelocytic leukaemia (APML)
In chronic leukaemia there is an accumulation of mature but abnormal white blood cells that have undergone a malignant change when developing from a blast cell. Chronic leukaemia progresses more slowly than acute leukaemia and may not require treatment for a long time after it is diagnosed.
Common forms of chronic leukaemia are: