Validation of Stockholm3 for prostate cancer detection in a swiss non-referral cohort: balancing biopsy reduction and diagnostic performance.

[PURPOSE] Prostate cancer (PCa) diagnosis relies on PSA testing, but its low specificity leads to overdiagnosis. Stockholm3 may improve diagnostic accuracy. This study evaluated the performance of Stockholm3 for detecting clinically significant PCa (csPCa), defined as ISUP grade ≥ 2 on biopsy, in a real-world, non-referral Swiss cohort.

[METHODS] Retrospective analysis of a prospective registry (2023-2025) at a non-referral urology practice in Switzerland. Initial screening was performed in men with PSA > 1.5 ng/mL or a suspicious digital rectal examination. Patients who underwent Stockholm3 and biopsy were included. We compared Stockholm3 with PSA, PSA density, and the SWOP risk calculator for the detection of csPCa in a pre-MRI diagnostic setting.

[RESULTS] We included 178 men (median age 65 years, IQR: 60.0-70.0). Among them, 60/178 (33.7%) had csPCa. Stockholm3 ≥ 15 showed sensitivity 0.78 (95% CI 0.67-0.88), specificity 0.44 (95% CI 0.35-0.54), and AUC 0.68 (95% CI 0.60-0.77). SWOP score > 4% showed sensitivity 0.42 (95% CI 0.30-0.55), specificity 0.78 (95% CI 0.70-0.85), and AUC 0.68 (95% CI 0.59-0.76). Both tests outperformed PSA > 3 ng/mL and PSA density > 0.15 ng/mL², with AUCs of 0.52 (95% CI 0.48-0.56) and 0.57 (95% CI 0.50-0.64), respectively. Decision curve analysis and calibration curves favored Stockholm3 over SWOP.

[CONCLUSIONS] In a non-referral setting, Stockholm3 confirmed good diagnostic performance for csPCa. These findings support its use as part of the primary diagnostic work-up in similar clinical settings.