Smoking and leukaemia

Smokers, especially those over the age of 60, are more than twice as likely as nonsmokers to develop a specific type of acute myeloid leukaemia (AML). Leukaemia is in lay terms known as 'blood cancer' because it is the white blood cells that become diseased. There are several types of Leukemia including AML. Here there is an increased number of immature blood cells known as blasts which can be seen in the blood, bone marrow, liver, spleen and lymph nodes. People with AML tend to have severe anaemia (i.e. markedly decreased iron in the blood) and are prone to infections, inflammation and blood clotting disorders. A recent study at the University of Southern California, Los Angeles associates smoking with an increased risk of AML. Earlier studies did not link the two because Leukemia and AML were not being analysed in their distinctive subtypes. As a result subtype-specific risk factors could not be discovered. In the present study eight different subtypes of AML (M0-M7) have been defined. Smoking plays a role in M2 but not in other subtypes and may be responsible for roughly 42% of cases of this subtype of leukaemia. The researchers observed 412 adults living in Los Angeles who were diagnosed with AML between 1987 and 1994. The patients were interviewed for their smoking habits and compared with 412 healthy people. While smokers in general were 2.3 times more likely to develop M2 type AML, older adults aged 60 to 75 years were at 3.3 times greater risk of developing the illness. Those who smoked unfiltered cigarettes for more than 35 years showed the highest risk but older adults who smoked filtered cigarettes also had almost a threefold higher risk compared with nonsmokers.

COMMENT