What is the definition or description of: prostate specific antigen?

A protein: Psa is a protein made in the prostate gland that functions to liquefy sperm. It is a serine protease made by both normal and malignant prostate glands. Commonly used as a screening test for prostate cancer, the psa test is widely used to detect which men would benefit from a prostate biopsy as well as detect cancer recurrence in men who have been treated for prostate cancer.

Blood test: Prostate-specific antigen, or psa, is a protein produced by cells of the prostate gland. The psa test measures the level of psa in a man’s blood. Level of psa is often elevated in men with prostate cancer.