ROC curve of PSA concentration shows a fair discriminant power with AUC = 0.70 (95% CI: 0.587–0.797) for differentiation between PCa and BPH with very high specificity and moderate sensitivity (97.5% and 47.5%, resp., cut-off value: 21.9 ng/mL). The gene discussed is KLK3; the disease is benign prostatic hyperplasia.