Number of screening rounds attended and incidence of high-risk prostate cancer in the Finnish Randomized Study of Screening for Prostate Cancer (FinRSPC).

BACKGROUND: The European Randomized Study of Screening for Prostate Cancer has shown a 20% reduction in prostate cancer (PC) mortality by prostate-specific antigen-based screening. In addition, screening has been shown to reduce the risk of advanced PC. The objective of the current study was to analyze the impact of screening participation on the incidence of PC by risk group. METHODS: The participants in the screening arm of the Finnish trial (31,867 men) were classified according to screening attendance in a time-dependent fashion. Initially, all men in the screening arm were regarded as nonattenders until the first screening attendance; they then remained in the once-screened group until the second screen and similarly for the possible third round. The control arm formed the reference group. Follow-up started at randomization and ended at the time of diagnosis of PC, emigration, or the end of 2015. PC cases were divided into risk groups according to European Association of Urology definitions. RESULTS: The incidence of low-risk PC increased with the number of screens, whereas no clear relation with participation was noted in the intermediate-risk and high-risk cases. For patients with advanced PC, attending screening at least twice was associated with a lower risk. CONCLUSIONS: Screening reduces the risk of advanced PC after only 2 screening cycles. A single screen demonstrated no benefit in terms of PC incidence. Repeated screening is necessary to achieve screening advantages.