Interpreting trends in prostate cancer incidence and mortality in the five Nordic countries

Trends in incidence and mortality rates of prostate cancer were analyzed using data from the national cancer registries of Denmark, Finland, Iceland, Norway, and Sweden. Joinpoint regression models were used to quantify temporal trends for the period from 1980 to 2004. Incidence rates were increasing and similar in the Nordic countries during the 1980s. Around 1990, a more rapid incidence increase began in all Nordic countries except Denmark, where an increase was seen 5 years later. In 2001, incidence rates in Denmark were half of those seen in the other Nordic countries, but mortality rates varied only marginally among countries. Mean annual declines in prostate cancer mortality of 1.9% (95% CI = 0.4% to 3.3%) and 1.8% (95% CI = 0.5% to 3.0%) were observed from 1996 to 2004 in Finland and Norway, respectively. During the same period, mortality rates leveled off in Iceland and Sweden but continued to increase in Denmark. The rapid increase in incidence during the early 1990s coincided with the introduction of the prostate-specific antigen (PSA) test and conveys little information about the occurrence of potentially lethal disease. Mortality rates, however, have recently stabilized or declined in countries where PSA testing and curative treatment have been commonly practiced since the late 1980s. Although other explanatory factors may be in operation, these trends are consistent with a moderate effect of increased curative treatment of early diagnosed prostate cancer and improved treatment of more advanced disease.