Epidemiology of non-Hodgkin's lymphoma: recent findings regarding an emerging epidemic.

Between 1973 and 1989, the incidence of non-Hodgkin's lymphoma (NHL) increased by nearly 60% in the United States, one of the largest increases of any cancer. In 1993, approximately 43,000 new cases of NHL will be diagnosed and over 20,000 deaths due to NHL will occur. The annual incidence rate of NHL per 100,000 persons in the US has risen from 5.9 in 1950 to 13.7 in 1989. This increase has occurred in both males and females, blacks and whites, and in all age groups except the very young. The largest increase has occurred in the elderly, and rates have increased more rapidly in rural areas. Most of the increase cannot be attributed to acquired immunodeficiency syndrome. Similar findings have been reported from other developed countries. Epidemiologic studies indicate that environmental factors may play an important role in the etiology of NHL. In this paper, current knowledge concerning the epidemiology of NHL is summarized, with special emphasis on environmental factors of possible etiologic importance, such as drugs, pesticides, solvents and other chemicals, dusts and particles, hair dyes, smoking, Helicobacter pylori infection, and diet. Many different environmental factors of low risk acting on large segments of the population could account for much of the increase in NHL.