The median age of patients who underwent secondary treatment (n = 142) for prostate cancer was 77.0 (75.0–93.0) years and the median PSA was 34.0 (3.4–4656.0) ng/ml; 76.0% of patients who underwent secondary treatment had GSs ≥8, and 34.5% of patients had metastatic prostate cancer. Here, KLK3 is linked to prostate cancer.