Increasing incidence of non-Hodgkin's lymphomas in Sweden 1958-1992

In recent years, there have been many reports from Europe and North-America describing non-Hodgkin's-lymphoma (NHL) as one of the most rapidly increasing malignancies. The reasons for this are poorly understood. This study describes the incidence pattern of NHL in Sweden during 1958-1992. A total of 26,925 cases (14,854 males and 12 071 females aged 15 years or older reported to the Swedish Cancer Registry between 1958 and 1992 were analysed. The increase in the age-adjusted incidence during this period was 433% among men and 386% among women, a mean yearly increase of 3.6% in men and 2.9% in women. The highest rates were seen during the most recent years and in the oldest age group, although there was a clear trend with increased age-adjusted incidence over time in both the male and the female groups in ages over 35. The incidence was low in the ages below 35 years. Known etiologic factors including viruses, environmental exposures and immunosuppression of different types are discussed. It is concluded that there has been a true increase in the age-adjusted incidence of non-Hodgkin's lymphomas in Sweden during the years 1958-1992.