Leukaemia: Symptoms, diagnosis and treatment
What is leukaemia?
Leukaemia is cancer of the blood. Unlike other cancers, leukaemia does not produce lump-like tumours but results in rampant overproduction of cancerous white blood cells. Leukaemia - the term derives from the Greek words for ‘white’ and ‘blood’ - is often considered a disease of children, yet it actually affects far more adults. It is more common in men than women. About 6,800 people get leukaemia in the UK each year. About 2,700 of these are acute leukaemia. The most common form is found more often in Caucasians.
Blood has three types of cells: white cells fight infection, red cells carry oxygen and platelets help to clot, all suspended in its liquid plasma. Every day, hundreds of billions of new blood cells are produced in the bone marrow - most of them red cells. In people with leukaemia, however, the body starts producing more white cells than it needs. Many of the extra white cells do not mature normally, yet they tend to live well beyond their normal life span.
Despite their vast numbers, these leukaemic cells are unable to fight infection the way normal white blood cells do. As they accumulate, they interfere with vital organ functions, including the production of healthy blood cells. Eventually the body does not have enough red cells to supply oxygen, enough platelets to ensure proper clotting, or enough normal white cells to fight infection, making people with leukaemia anaemic and susceptible to bruising, bleeding and infection.
Cases of leukaemia are classified as acute or chronic. Cancer cells in acute leukaemias start multiplying before they develop beyond their immature stage. Chronic leukaemias progress more slowly, with cancer cells developing to full maturity. Leukaemias are further classified according to the type of white blood cell involved. Under a microscope, two main types of white blood cells are easily distinguishable: Myeloid cells contain tiny particles or granules; lymphoid cells usually do not.
What causes leukaemia?
No-one knows exactly what causes leukaemia. But chromosome abnormalities are associated with leukaemia and with a pre-leukaemic disease called myelodysplasia. Nine out of 10 people with CML (chronic myeloid leukaemia), for example, have an abnormal chromosome called the Philadelphia Chromosome in their blood cells. As with other leukaemias, this chromosome is an acquired abnormality; it is neither inherited nor passed on to one's children. Chromosome abnormalities associated with congenital disorders such as Down’s syndrome strongly correlate with certain types of leukaemia, and at least one virus in the same family as the human immunodeficiency virus (HIV) has been associated with a rare form of the disease.
Environmental factors seem to influence the risk of developing leukaemia. Tobacco smokers are more prone to certain leukaemias than non-smokers. Research also suggests that prolonged exposure to radiation, various chemicals in home and work environments, and low-frequency electromagnetic fields may be associated with leukaemia, but there is no definitive proof.
Leukaemia is also a rare complication of chemotherapy or radiotherapy when used to treat other cancers.