KLK3 and prostate cancer: Besides, PSA is unable to differentiate between indolent and aggressive forms of prostate cancer, which may ignore aggressive prostate cancer with low initial serum PSA levels.187,190 All the aforementioned factors make prostate cancer now an “overdiagnosed” and “overtreated” cancer.185 To sum up, PSA level is a promising biomarker in prostate cancer diagnosis and prediction.