The area under the receiver operating characteristic curve (AUC) of PSAD was significantly greater than PSA in patients with significant prostate cancer in the PSA range of 4–10 ng/mL (AUC: 0.72 vs. 0.57, p < 0.0001) and PSA > 10 ng/mL (AUC: 0.82 vs. 0.68, p < 0.0001) [3]. Here, KLK3 is linked to prostate cancer.