TRENDS IN STAGE-SPECIFIC INCIDENCE OF PROSTATE CANCER IN NORWAY, 1980-2010: A POPULATION-BASED STUDY
Method: From the Cancer Registry of Norway we obtained cancer stage, age and year of diagnosis on all men over the age of 50 diagnosed with PC during the period 1980-2010 in Norway. Three calendar-time periods were defined: One before the introduction of PSA-testing (1980-1989) and two after reflecting increasing diagnostic intensity (1990-2000 and 2001-2010); and three age groups: men eligible for PSA-testing (50-65 and 66-74) or older (75+). Birth-cohorts were categorized into four intervals: <1910, 1916-1925, 1926-1940 and >1941. We used Poisson regression to conduct a cross-sectional and a cohort-based analysis of trends in the incidence of localised, regional and distant cancer, respectively.
Result: The annual incidence of localised PC among men aged 50-65 and 66-74 rose from 41.4 and 255.2 per 100,000 before the introduction of PSA-testing to 137.9 and 418.7 in 2001-2010 afterwards, respectively, corresponding to 3.3 (CI: 3.1; 3.5) and 1.6 (CI: 1.6; 1.7) fold increases. The incidence of regional cancers increased by a factor seven and four among men aged <75 and 75+, respectively. The incidence of distant cancers among men aged 75+ decreased from 218.8 to 155.1 per 100,000, corresponding to a decrease of 0.7 (CI: 0.7; 0.8). The cohort-based analysis showed that the incidence of localised and regional PC shifted downwards to younger men, with a gradually decreased incidence of distant cancer in more recent cohorts.
Conclusion: Opportunistic PSA-testing substantially increased the incidence of localised and regional PC among men aged 50-74 years. The increase was not fully compensated in absolute numbers by the decrease in incidence of distant PC in older men, although it decreased by 30%.