Prostate-specific antigen and prostate cancer: prediction, detection and monitoring

Prostate-specific antigen (PSA) is one of the few molecular markers routinely used for detection, risk stratification and monitoring of a common cancer.PSA is specific to the prostate but not to prostate cancer: benign prostate diseases often cause increases in serum PSA and most men with increased PSA do not have prostate cancer.PSA strongly discriminates different cancer stages: it is higher in men with localized disease than in cancer-free controls, is associated with stage and grade in localized disease and is higher in patients with metastatic compared with localized disease.Men with a higher PSA at the time of initial therapy have increased risk of recurrence.PSA is a sensitive indicator of recurrence after radical prostatectomy, but far less sensitive as an indicator of recurrence after radiation therapy.PSA before age 50 is a strong predictor of prostate cancer occurring up to 25 years later.The introduction of PSA as a screening test has led to a sharp increase in the incidence of prostate cancer because there has been a shift to diagnosis at earlier stages and there is probably substantial 'overdiagnosis' — men diagnosed with prostate cancer whose cancer would never have affected their lives if they had not had a PSA test.The effects of PSA screening on prostate cancer mortality are not yet clear.