However, approximately 15% of PCa patients still presented with normal PSA levels or below 4.0 ng/ml [9], which led to false negatives and limited sensitivity for PCa diagnosis because the elevated PSA values were also caused by other non-cancerous factors including age, infection, prostatitis, and benign prostatic hyperplasia (BPH) [10]. This evidence concerns the gene KLK3 and prostatitis.