Epidemiology of human leukemia.

The leukemias show clear geographic, racial, ethnic, age, and gender variation in both incidence and mortality, and the patterns of occurrence differ among subtypes. Despite decades of epidemiologic study, the known and suspected risk factors for leukemia are insufficient to explain more than a small fraction of the observed variation in the occurrence of the leukemias. Important contributions to the literature in 1993 included studies further clarifying the role of known risk factors (ionizing radiation, certain chemotherapeutic agents, and specific occupational chemical exposures) and suspected risk factors (infectious agents, electromagnetic fields, cigarette smoking, other chemotherapeutic agents, and additional occupational chemical exposures) in leukemogenesis.