On one hand, nearly 15–25% of men have PCa even though their PSA levels are normal (4.0 ng/mL or less) [32], [33].On the other hand, high PSA levels are observed in men with benign prostate enlargement (BPH), prostatitis or indolent cancers [34], and data suggests that an estimated 40% to 50% of cases undergo unnecessary overtreatment. Here, KLK3 is linked to prostatitis.