Results of the three rounds of the Finnish Prostate Cancer Screening Trial--the incidence of advanced cancer is decreased by screening. 
Screening for prostate cancer (PC) remains a controversial issue despite some new evidence on the mortality benefits of PC screening.  We conducted a prospective, randomized screening trial in Finland to investigate whether screening decreases PC incidence.  Here, we report the incidence results from three screening rounds during a 12-year period.  Of the 80,144 men enrolled, 31,866 men were randomized to the screening arm (SA) and invited for screening with prostate-specific antigen test (cut-off 4.0 ng/ml) every 4 years, while the remaining men formed the control arm (CA) that received no interventions.  The mean follow-up time for PC incidence in both arms was over 9 years.  The incidence rate of PC (including screen-detected and interval cancers as well as cases among nonparticipants) was 9.1 per 1,000 person-years in the SA and 6.2 in the CA, yielding an incidence rate ratio (IRR) 1.5 (95% confidence interval 1.4-1.5).  The incidence of advanced PC was 1.1 in the SA and 1.5 in the CA, IRR = 0.7 (0.6-0.8) and the difference emerges after 5-6 years of follow-up.  The incidence of localized PC was 7.5 in the SA and 4.6 in the CA, IRR = 1.6 (1.5-1.7).  The results from our large population-based trial indicate that screening for PC decreases the incidence of advanced PC.  When compared with the CA, the PC detected in the SA there were substantially more often localized, low-grade PCs due to overdiagnosis.