Leukaemias in Africa.

Until recently, cALL has been uncommon in sub-Saharan Africa, but there is now emerging a peak of incidence at the age 3 to 5 years in west and southern Africa. Prognosis for African patients with cALL is poor because of a multitude of clinical, biological and social factors. AML is seen at high frequency (probably indicating truly high incidence) in male children 5-14 years, of whom up to a quarter present with chloroma. It is predicted that the incidence of AML in adults may rise in the near future, related to cigarette smoking, occupational and environmental exposures to benzene and other pollutants, and the prescription of alkylating agents to young people with malignant disease. CML shows no particular epidemiological features, except for a high frequency in young adults and children, reflecting the age structure of the whole population. There are two forms of B-CLL: one is seen most commonly in women of low socioeconomic status towards the end of the their reproductive life, and is probably related to an initially polyclonal expansion of B-cells in response of recurrent malaria and other infections; the other is seen over the age of 45 years, with men being affected twice as commonly as women, as in the western world.