Changing incidence of non-Hodgkin lymphomas in the United States

The incidence of non-Hodgkin lymphoma (NHL) has been rising in many regions and populations during the last few decades. Data from the Surveillance, Epidemiology, and End Results (SEER) Program show that age-adjusted rates of NHL increased through the 1980s but leveled off in the 1990s.

To determine whether the incidence of NHL stabilized in all population subgroups, particularly in age-defined groups with distinctive risks of NHL, the authors investigated trends in NHL incidence among persons aged 0-14 years, 15-24 years, 25-34 years, 35-44 years, 45-54 years, 55-64 years, 65-74 years, and > 75 years by gender and race using 1973-1998 data from the SEER Program, which covered approximately 10% of the U.S. population. Joinpoint regression was used to assess changes in trends across the period.

NHL incidence trends changed significantly among males aged 25-54 years, in whom rates began to decrease (6-16% per year) in the middle to late 1990s, as well as among most whites aged > or = 55 years, in whom rate increases slowed from 3-4% to 1-2% per year in the late 1980s. Incidence trends were steady in other groups, with uniform increases among whites aged 15-24 years (2-3% per year), women aged 25-54 years (1-6% per year), and blacks aged > or = 55 years (2-4% per year). Although recent age specific incidence rates were generally higher in males compared with females and in whites compared with blacks, among males aged 25-54 years, rates were significantly higher in black males compared with white males.

There have been changes in the demographic groups impacted by NHL. The trends for human immunodeficiency virus probably are related to recent decreases in NHL incidence among males aged 25-54 years. The rate change in the older white population is unexplained but represents both an alleviation of the burden of NHL in this population and a potential opportunity to generate hypotheses regarding risk factors for the development of NHL.