(6) Prostate Disorders
What is Prostate-Specific Antigen (PSA)?
PSA is a serine protease that was originally identified and isolated in the seminal plasma. The physiologic role of PSA is the liquefaction of semen. PSA is made by both benign and cancerous (malignant) prostate tissue, although malignant prostate tissue makes about 20 times more PSA per gram than benign tissue.
Therefore, an elevation of serum PSA can be seen with either benign or malignant growth of the prostate. For all intents and purposes, PSA is made only by prostate tissue and not by any other cells in the body. PSA has therefore gained widespread use as a tumor marker to aid in the diagnosis and management of prostate cancer.
Is PSA the only marker in the blood that signals the possibility of prostate cancer?
Serine protease - a class of peptidases found in the blood.
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