Testicular cancer incidence in eight northern European countries: secular and recent trends.
OBJECTIVE
Striking geographic variation and marked increasing secular trends characterize the incidence of testicular cancer. However, it is not known whether these patterns have attenuated in recent years and whether they are similar for seminomas and nonseminomas, the two main histologic groups of testicular cancer.


METHODS
Cancer registry data, including 27,030 testicular cancer cases, were obtained from Denmark, Estonia, Finland, Latvia, Lithuania, Norway, Poland, and Sweden. Between 57 (Denmark) and 9 (Poland) years of registration were covered. Country-specific temporal trends were estimated, with focus on the last decade and seminomas and nonseminomas. Data from the Nordic countries were further analyzed using an age-period-cohort approach.


RESULTS
Age-standardized incidence rates increased annually by 2.6% to 4.9% during the study period, with marginal differences between seminomas and nonseminomas. In the last decade, the increasing trend attenuated only in Denmark (annual change, -0.3%; 95% confidence interval, -1.5 to 0.9). In 1995, the highest and the lowest age-standardized incidence rates (per 10(5)) were 15.2 in Denmark and 2.1 in Lithuania. Incidence rates (i.e., for all cancers and for seminomas and nonseminomas, separately) depended chiefly on birth cohort rather than on calendar period of diagnosis (although both birth cohort and period determined the Danish incidence rates).


CONCLUSIONS
Testicular cancer incidence is still increasing, with the exception of Denmark, and a large geographic difference exists. The increasing trend is mainly a birth cohort phenomenon also in recent cohorts. Temporal trends for seminomas and nonseminomas are similar, which suggests that they share important causal factors.
Richiardi
Lorenzo
L
Department of Medicine, Karolinska Hospital, Stockholm, Sweden. lorenzo.richiardi@unito.it
Bellocco
Rino
R
Adami
Hans-Olov
HO
Torrång
Anna
A
Barlow
Lotti
L
Hakulinen
Timo
T
Rahu
Mati
M
Stengrevics
Aivars
A
Storm
Hans
H
Tretli
Steinar
S
Kurtinaitis
Juozas
J
Tyczynski
Jerzy E
JE
Akre
Olof
O
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D016021:Epidemiologic Studies; D005060:Europe / Q000453:epidemiology; D005843:Geography; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012042:Registries / Q000706:statistics & numerical data*; D018239:Seminoma / Q000453:epidemiology*; D013736:Testicular Neoplasms / Q000453:epidemiology*