Chronic myeloid leukaemia or CML often begins when there is a change in the structure of DNA that affects the regulation of growth and maturity of the stem cells that produce white blood cells, red blood cells and platelets.
The DNA provides the cells important information about when to grow, multiply or die. The mutation in the DNA changes these instructions making the stem cells produce more white blood cells than are needed.
These stem cells are present in the bone marrow. The bone marrow is the spongy material that lies within the long bones in the body. As the stem cells begin to proliferate uncontrollably, they begin to overcrowd the normal cells and there is a lack of production of the cells other than the myeloid cells in CML.
Furthermore these myeloid cells that the stem cells produce are immature white blood cells (also called blast cells) that are incapable of performing their normal task of fighting infections.
Triggers for CML
The cause or trigger that can lead to the mutation of the DNA and make it cancerous is still unknown. However, certain risk factors that may increase the chances of getting CML include:-
This is one of the most significant risk factors that raise the chance of getting CML. High radiation exposure such as after an atomic bomb explosion in Hiroshima or after a nuclear reactor accident such as the one at Chernobyl have been directly associated with an increased incidence of CML among survivors.
Radiation exposure due to routine X ray examinations and CT scans however are not strongly associated with CML. Those individuals, however, who are exposed to radiation as part of their occupation may be at risk of developing CML.
There is some evidence that long term exposure to the chemical benzene leads to an increased risk of chronic myeloid leukaemia. Benzene is found in petrol, cigarettes etc. and is also used in the rubber industry. Benzene is more closely associated with causing acute myeloid leukemia (AML) than CML.
Age, gender and family history
The risk of getting CML rises with age. The disease is also slightly more common in males than females. The risk of CML does not seem to run in families.
Exposures to pesticides among agriculture workers, exposure to chemicals among rubber or plastic manufacture workers, cleaners, builder’s labourers, hairdressers etc. have all been studied as risk factors for developing CML.