Abstract: PD40-03
Sources of Funding: Pirkanmaa Hospital District, memorial fund of Seppo Nieminen.

Introduction

Prostate cancer (PCa) screening with prostate-specific antigen (PSA) reduces PCa mortality, but leads to overdiagnosis of indolent PCa. Use of 5-alpha reductase inhibitors (5-ARIs) lowers PSA and in theory could affect performance of PSA-based screening. We evaluated outcomes of PCa screening among 5-ARI users.

Methods

The study was performed within the Finnish Randomized Study of Screening for Prostate Cancer. Of 80,454 men, 31,866 were randomized to be screened at four-year intervals during 1996-2004. Information on 5-ARI reimbursements before PCa during 1995-2009 was collected from the national prescription database for 78,615 men. We evaluated the effect of screening on PCa risk and mortality by 5-ARI usage using Cox regression.

Results

Men using 5-ARIs had higher median PSA and were more often screen-positive compared to non-users. Despite this, screening did not significantly affect PCa detection (HR 0.89, 95% CI 0.79-1.01) or mortality (HR 0.82, 95% CI 0.51-1.32) compared to the control arm among 5-ARI users. In ROC analysis, PSA and age did not predict Gleason 7-10 prostate cancer as accurately in 5-ARI users as among the non-users (AUC = 0.88 versus 0.79 in the first screening round).

Conclusions

PSA-based screening among men using 5-ARIs does not improve detection of high-grade or metastatic PCa or prevention of PCa deaths. Targeted screening should focus on men not using 5-ARIs.

Funding

Pirkanmaa Hospital District, memorial fund of Seppo Nieminen.