Non-Hodgkin's lymphoma subtypes over time in an unselected population of 646 patients: a study of clinico-pathological data and incidence based on a review using the REAL-classification.

Biopsies from 646 consecutive unselected cases of non-Hodgkin's lymphoma from a Danish population-based registry were reclassified according to the REAL classification 1) to study the distribution of subtypes over time, and 2) to correlate a number of clinical parameters with the various subtypes. Two cohorts from 1986 and 1992, of 292 and 354 cases, respectively, were studied. From 1986 to 1992 diffuse large B-cell lymphoma showed a change in incidence of + 43.1%, as opposed + 2.5% for all other subtypes combined (p = 0.05), suggesting that the increasing general incidence of non-Hodgkin's lymphoma is due primarily to an increasing incidence of diffuse large B-cell lymphoma. A higher rate of cell proliferation was associated with an increasing chance of having extranodal disease. For the various subgroups there was good agreement between survival and the International prognostic index.