PSA is a substance which is produced only by the prostate gland. Its measurement is done exclusively to help detect prostate cancer.

PSA testing has dramatically increased the number of men diagnosed with prostate cancer to approximately 200,000 per year. While PSA has revolutionized the detection of prostate cancer, it is not a perfect test. False positives and false negatives may occur. The use of PSA should ideally be combined with a physical exam to help detect prostate cancer. The American Urological Association recommends PSA testing in all men 50 years old and above.