When serum PSA levels were divided into five subgroups (less than 4.0, 4.0 to 10.0, 10.0 to 20.0, 20.0 to 100.0, and ≥ 100.0 ng/ml), the detection rates of prostate cancer were 12.4, 15.9, 34.1, 66.2, and 93.8%, respectively. Here, KLK3 is linked to prostate cancer.