Bladder cancer (BCa) diagnosis and surveillance rely heavily on invasive cystoscopy and urine cytology, which has limited sensitivity, underscoring the need for reliable non-invasive biomarkers. ENOX2 (tumor-associated NOX) is a candidate pan-cancer biomarker shed from tumor cell membranes into biological fluids, but its utility in BCa remains unexplored. This prospective pilot study enrolled 33 non-muscle-invasive bladder cancer (NMIBC) cases, 32 non-cancer controls for the primary analysis, and 38 other cancer controls. Serum and urinary ENOX2 were measured by ELISA, and ENOX2 gene expression by qPCR. Diagnostic performance was assessed using receiver operating characteristic (ROC) curve analysis and the area under the curve (AUC). The urinary ENOX2/creatinine ratio was significantly higher in NMIBC cases than controls (median 17.95 vs 0.74 ng/mg, p = 0.018), achieving the highest diagnostic performance among studied markers (AUC 0.670, with sensitivity 53% and specificity 91% at a cutoff of ≥17.85 ng/mg), while serum ENOX2 and qPCR expression showed no diagnostic utility (AUC 0.435 and 0.417, respectively). Further exploratory analyses showed that the urinary ENOX2/creatinine ratio demonstrated comparable AUC across low- and high-grade tumors and correlated with tumor size. Additionally, the levels did not vary across benign urological conditions. The urinary ENOX2/creatinine ratio demonstrates modest but statistically significant diagnostic utility in NMIBC, outperforming serum ENOX2 measures in this pilot study. Further evaluation of ENOX2 in larger, multicenter cohorts, including its potential role within multimarker diagnostic panels, is recommended.

Introduction: Multiparametric MRI (mpMRI) interpreted using Prostate Imaging Reporting and Data System (PI-RADS) v2.1 is central to prostate cancer (PCa) assessment, but inter-reader variability remains a concern. This study evaluated inter-reader agreement, diagnostic performance, the utility of prostate-specific antigen density (PSA-D), and imaging predictors of biopsy-detected PCa. Methods: We conducted a retrospective study of 102 patients who underwent prostate mpMRI followed by transrectal ultrasound (TRUS)-guided biopsy. Three experienced radiologists independently scored examinations using PI-RADS v2.1. Agreement was assessed using intraclass correlation coefficients (ICC) and weighted κ statistics. Diagnostic performance was evaluated at a PI-RADS ≥3 threshold. Patients were stratified by PSA-D, and logistic regression identified imaging predictors of biopsy outcomes. Reader confidence was scored on a 10-point scale. Results: PCa was detected in 60/102 patients (58.8%) and csPCa in 46/102 (45.1%). Overall agreement was moderate to good (ICC, 0.749; κ, 0.748), with higher agreement in the transitional compared to the peripheral zone (ICC, 0.822 vs. 0.662). Averaged PI-RADS scores yielded 100% sensitivity for both PCa and csPCa, with specificities of 47.6% and 35.7%, respectively. PSA-D stratification showed higher PPVs at PSA-D ≥0.15 ng/mL², while sensitivity and NPV were 100% in both strata; specificity remained relatively low. Reader confidence correlated with PI-RADS category and interpretation accuracy. In multivariable patient-level analyses, DWI hyperintensity was independently associated with biopsy-detected PCa and csPCa. Conclusions: PI-RADS v2.1 showed moderate to good inter-reader agreement and high sensitivity but modest specificity for PCa and csPCa. Agreement was higher for transitional-zone lesions, and DWI hyperintensity was independently associated with PCa and csPCa. PSA-D subgroup estimates were imprecise, and its incremental value requires confirmation in larger prospective cohorts.