The PHI has been shown to improve the area under the curve (AUC) versus PSA for the detection of all prostate cancers, regardless of risk group (AUC: PHI = 0.708 vs. PSA = 0.516) and for the detection of high-grade PCa (Gleason ≥7): AUC: PHI = 0.707 vs. PSA = 0.551 [12]. The gene discussed is KLK3; the disease is prostate cancer.