Incidence-based analysis of lethal prostate cancer in Swedish counties with high versus low incidence of prostate cancer in nationwide, population-based registries.

Abstract

4668 Background: Current data from randomized trials differ in the ratio of benefit to harms from screening for prostate cancer (PC) using prostate specific antigen (PSA) testing and it is further unclear if decreases in PC mortality in the US can be attributed to introduction of screening or to changes in treatment. The aim of this study was to investigate if rapidly increased incidence of PC diagnosis due to early and rapidly increased rate of PSA testing, is associated with decreased incidence of lethal PC. Methods: In this incidence-based study using highly representative data from nation-wide population-based registries we analysed the incidence of lethal prostate cancer in eight Swedish counties with the most rapid and largest increased incidence of PC diagnosis (high incidence counties) from 1995 through 2002, and six counties with the smallest increased PC incidence (low incidence counties). We analysed the rate ratio (RR) in high vs. low incidence counties of cases with metastatic PC at diagnosis, (positive bone scan or PSA above 100 ng/ml), PC-specific mortality, and excess mortality (death among PC cases regardless of cause). Participants were men aged 50-74 years during 2000 to 2009 in the high versus low incidence counties contributing 4,528,134 versus 2,471,373 person-years at risk, respectively. There were 33,780 incident PC diagnoses and 1,577 PC deaths in high incidence counties and 16,377 PC cases and 985 PC deaths in low incidence counties. Results: In high vs. low incidence counties, RR of metastatic PC was 0.85 (95% confidence interval [CI] = 0.79 to 0.92), RR of PC-specific mortality was 0.87 (95% CI = 0.81 to 0.95) and RR of excess mortality in men with PC was 0.75 (95 %CI = 0.66 to 0.86). Conclusions: Our study provides data on a population-level indicating a decreased incidence of lethal PC in areas with rapid and large increase in incident PC diagnosis due to increased rates of PSA testing, early diagnosis, and treatment with curative intent.