The epidemiology of non-Hodgkin's lymphoma: why the increased incidence?

The incidence of non-Hodgkin's lymphoma continues to increase in the United States. Improvements in diagnostic techniques, changes in disease classifications, and the increase in AIDS-related lymphomas account for only a small percentage of the increase, leaving most of the increased incidence unexplained. Viruses clearly play a major role in the pathogenesis of some subtypes of non-Hodgkin's lymphoma, especially Epstein-Barr virus and HTLV-1, and improvements in molecular diagnostic techniques may identify additional viruses that have a role in the pathogenesis of lymphomas. Immunodeficiencies, whether acquired, congenital, or iatrogenic, clearly predispose to the development of non-Hodgkin's lymphoma. Numerous environmental exposures have also been linked to an increased risk of non-Hodgkin's lymphoma and may account for a portion of the continuing increased incidence of the disease.