RISING INCIDENCE OF NON-HODGKINS-LYMPHOMA IN SPAIN - ANALYSIS OF PERIOD OF DIAGNOSIS AND COHORT EFFECTS

Incidence trends in non-Hodgkin's lymphomas for the period 1973-1991 w ere studied using data from Spain's Zaragoza and Navarre registries. T he overall rate of increase was 5.8% per year. Age-period-cohort model s were used, also including sex and registry as explanatory variables. In these models, the variable period was categorized according to the observed changes in diagnostic availability during the length of the study. Non-Hodgkin's lymphomas increased with age, and rates were 31% lower in women. Incidence was almost 50% higher in Navarre, but differ ences in registry procedures might account for this discrepancy. The r ise affects all adult age groups and seems to be the result of changes related not only to the period of diagnosis, mainly ascribable to imp rovements in diagnostic and coding practices, but also to the birth co hort. According to the model, the risk increased with on-coming genera tions at a rate of 1.5% per gear. The AIDS epidemic in Spain is unable to explain this trend, although it mag well exert a stronger influenc e in the future, Additional knowledge is required to understand the ob served rise and to prevent the growing numbers of cases that are expec ted in years to come.