Time trends in the registration of Hodgkin and non-Hodgkin lymphomas in Europe.

Lymphoma incidence is reported to be increasing globally. If real, these trends can only be explained by an increasing exposure to risk(s) as yet unknown. There have been numerous coding and classification changes over time and greater access to ever more sensitive diagnostic tests. It is important to understand the consequences that these changes, coupled with general improvements in cancer registration, have had on observed temporal trends. Trends in the registration rates of both non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL) in Europe are presented. Age-adjusted and age-specific rates are described in men and women in 13 European countries according to both period of diagnosis and year of birth. Age, period and cohort effects are modelled. Overall, there are increases in the numbers of NHL registrations made with a corresponding decrease in HL. In recent history, however, there is a suggestion that the rate of increase is less and stable.