Incidence of non-Hodgkin's lymphoma in Sweden, Denmark, and Finland from 1960 through 2003: an epidemic that was.
BACKGROUND
Reports during the early 1990s indicated non-Hodgkin's lymphoma (NHL) as one of the most rapidly increasing malignancies. More recent trends remain poorly characterized, as do the underlying reasons for NHL time trends, in particular, the effect of changes in classification and registration of lymphoproliferative malignancies. Insights into the descriptive epidemiology of NHL may shed light upon its elusive etiology.


METHODS
We used data from the Swedish, Danish, and Finnish national cancer registers to assess the incidences of NHL and other lymphoproliferative malignancies between 1960 and 2004. Using Poisson regression, we estimated the annual rate of change in NHL incidence per decade by sex, age, and country.


RESULTS
In Sweden, Denmark, and Finland, the NHL incidence increased in both genders and all age categories by about 4% every year up until the early 1990s. Thereafter, the incidence increased at a slower rate (ages 60-79 years), stabilized (ages 50-59 and > or =80 years), and decreased (ages 0-49 years), respectively, similarly for males and females in the three countries. Time trends of NHL were not reciprocated and explained by trends for other lymphoproliferative malignancies nor explained by trends in NHL as secondary primaries or NHL diagnosed postmortem.


CONCLUSIONS
The epidemic increase of NHL has recently subsided. Changes in the classification of lymphoproliferative malignancies, or occurrence of NHL as second primaries, only offer a marginal explanation.
Sandin
Sven
S
Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden.
Hjalgrim
Henrik
H
Glimelius
Bengt
B
Rostgaard
Klaus
K
Pukkala
Eero
E
Askling
Johan
J
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003718:Denmark / Q000453:epidemiology; D016021:Epidemiologic Studies; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008228:Lymphoma, Non-Hodgkin / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D012042:Registries; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors