Leukaemia is a cancer of the white blood cells (leukocytes) and the term Leukaemia comes from the Greek words for white and blood. Leukaemia accounts for about 30% to 40% of all childhood cancers in Singapore and throughout the world1. Leukaemia starts in the bone marrow, the spongy internal part of the bones where new blood is made, and the abnormal white blood cells then spread to the blood stream.
When a child has Leukaemia, large numbers of abnormal white blood cells called blasts are produced in the bone marrow. These abnormal white blood cells crowd the bone marrow and cause it to be unable to perform its normal function of producing mature red blood cells, white blood cells and platelets.
As the Leukaemia progresses, other types of blood cell production such as red blood cells and platelets are affected. The Leukaemia cells flood the bloodstream and infiltrate other organs, especially the lymph nodes, liver and spleen. However, they do not protect the body against diseases as normal ones do because they are defective and immature and this may result in an increased risk of infections. As red blood cell and platelet production is also decreased, anaemia and bleeding tendencies may occur.
There are two types of Leukaemia, acute (rapidly developing) and chronic (slowly developing). About 5% of leukaemia in children are chronic while 95% are acute2. There are two types of chronic leukaemia - Chronic Myelogenous Leukaemia (CML) and Chronic Lymphocytic Leukaemia (CLL). CML occurs very rarely in children.
Acute Childhood Leukaemia is divided into Acute Lymphocytic Leukaemia (ALL) and Acute Myelogenous Leukaemia (AML). This categorisation depends on which cell line (mother cell) the Leukaemia starts from. Approximately 80% of children with leukaemia have ALL and about 20% have AML3.
Most ALL cases commonly occur in early childhood, peaking between 2 and 4 years of age. Cases of AML are more spread out across the childhood years but they are slightly more common during the first 2 years of life and during the teenage years.
There is currently no known way to prevent childhood Leukaemia. The cause of Leukaemia is unknown in majority of the cases. Most Leukaemia develop from non-inherited mutations (changes) in the genes of growing blood cells. Neither parents nor children have control over the factors that trigger Leukaemia.