Homogeneous prostate cancer mortality in the Nordic countries over four decades

Abstract

Background: Incidence of prostate cancer (PCa) has greatly increased in the Nordic region over the past two decades, following the advent of prostate-specific antigen (PSA) screening. Consequently, interpreting temporal trends in PCa has become difficult, and the impact of changes in exposure to causal factors is uncertain.

Objective: To reveal geographic differences and temporal trends in PCa in the Nordic countries. Because the recorded incidence of PCa has been profoundly influenced by PSA screening, we focused our analyses primarily on PCa mortality.

Design, setting, and participants: We analyzed national PCa incidence and mortality data from Denmark, Finland, Norway, and Sweden from 1965 to 2006 using the PC-NORDCAN software program and the online NORDCAN database.

Measurements: Cumulative incidence and cumulative mortality from PCa were calculated for selected calendar years during four decades, along with age-standardized mortality rates. Incidence data in NORDCAN come from individual countries' cancer registries, and mortality data come from national mortality registries.

Results and limitations: From 1965 to 2006, 172 613 deaths from PCa were reported in the four Nordic countries. A substantial rise in incidence was observed across the region, with some geographic variation, since the late 1980s. In contrast, both disease-specific mortality rates and cumulative risk of PCa mortality lacked consistent temporal trends over the same period. Cumulative mortality from PCa ranged between 3.5% and 7.5% in the region over four decades, whereas cumulative incidence jumped from about 9% to >20%. Mortality has remained fairly constant among the countries, with a minimally lower risk in Finland.

Conclusions: Unlike most malignancies, the occurrence of lethal PCa showed minimal geographic variation and lacked consistent temporal trends over four decades. These findings may guide our search for important causes of PCa, a malignancy with etiology that is still largely unknown.