Prostate Specific Antigen (PSA) Serum
Prostate specific antigen (PSA) is a glycoprotein produced exclusively by the epithelial cells lining the prostatic ducts and acini. Normally, it is secreted into the prostatic ducts and is present only in prostate tissue, prostatic fluid, and seminal plasma. PSA is produced by normal, hyperplastic, and cancerous prostatic tissue. In recent years, urologists have found serum PSA to be the most sensitive marker for monitoring patients with known prostate cancer. In these patients, serum PSA levels are used to predict survival and tumor recurrence following therapy. Serum PSA levels are frequently monitored in conjunction with another serum marker for prostatic cancer: prostatic acid phosphatase (PAP). Although PAP is not as sensitive for prostatic cancer as PSA, concurrent use of the two markers has been shown to enhance efficacy in monitoring progression of disease and response to therapy.