Leukaemias These are the most common cause of malignant disease in children. However, leukaemia can develop at any age and, in most countries, the majority of people who get leukaemia are over the age of 55. The commonest childhood leukaemia is acute lymphocytic leukaemia whereas aging adults tend to get chronic granulocytic leukaemia. There are multiple factors that cause leukaemias, but there are some groups of people who are more likely to get them. These include people exposed to ionising radiations or to certain chemicals, or those born with particular congenital abnormalities. Characteristically, there is a problem in the production of new blood cells in the bone marrow of the body. The most primitive blood cells in the series develop faults, and they cannot be induced to change normally into mature forms which should circulate in the blood. These immature, malfunctioning cells accumulate in the bone marrow, and upset normal blood cell development. Thus the blood may contain fewer cells than normal of a particular type, and in addition a few leukaemic cells may escape into the blood. So an examination of the blood in patients reporting aching and tender bones, enlarged joints or severe anaemia is generally followed by an examination of the bone marrow to see if abnormal cells are present there. Often in acute leukaemia the lymph nodes and spleen swell. Treatment of leukaemias today is quite effective, but death may result from secondary problems such as infections, bleeding and failure of the kidneys and/or liver.