Abstract
OBJECTIVES: This study aimed to evaluate the clinical utility of the SelectMDx urinary biomarker test in men with PI-RADS 3 lesions identified through multiparametric magnetic resonance imaging (mpMRI), a subgroup in which prostate cancer diagnosis remains uncertain. The primary objective was to assess whether SelectMDx can improve risk stratification for clinically significant prostate cancer and thereby reduce unnecessary prostate biopsies. MATERIALS AND METHODS: A prospective cohort of 40 patients with serum prostate-specific antigen (PSA) levels ≥3 ng/mL and PI-RADS ≥ 3 lesions on mpMRI was analyzed. All participants underwent mpMRI, followed by targeted magnetic resonance imaging/transrectal ultrasound (MRI/TRUS) fusion-guided biopsy and standard TRUS-guided biopsy. Prior to biopsy, urine samples were collected post-digital rectal examination for SelectMDx analysis. The test evaluates messenger ribonucleic acid (mRNA) expression of distal-less homeobox 1 (DLX1) and homeobox C6 protein (HOXC6), integrating molecular data with clinical parameters to generate individualized risk scores. Diagnostic performance was assessed through sensitivity, specificity, predictive values and logistic regression analyses. RESULTS: Among patients with PI-RADS 3 lesions (n=40), a significant correlation between SelectMDx results and biopsy-confirmed clinically significant prostate cancer was observed. Clinically significant cancer was detected in 57.1% of patients with a positive SelectMDx result, compared to 18.2% in those with a negative result (p=0.031). The test demonstrated a sensitivity of 57.14%, a specificity of 81.82%, a positive predictive value of 40% and a negative predictive value of 90%, with an overall diagnostic accuracy of 77.5%. While age emerged as the only independent predictor in multivariate analysis, SelectMDx showed a strong potential to exclude malignancy and support more selective biopsy strategies.