In 1986, PSA was approved by the FDA as an adjunctive test for the detection of prostate cancer in men over the age of 50.185,189 Subsequently, in 1994, PSA was approved by the FDA as a diagnostic biomarker.189 Later on, PSA became popular in prostate cancer detection and patient management including screening, risk stratification for recurrence, surveillance following diagnosis, and monitoring therapy.186,188 Total PSA essentially consists of free PSA and bound PSA, and the higher percentage of the free PSA is connected to the lower the cancer risk. Here, KLK3 is linked to Familial prostate cancer.