Prostate-Specific Antigen: Its Role in Early Detection, Staging, and Monitoring of Prostatic Carcinoma

Abstract
Prostate-specific antigen (PSA) is a significant improvement over prostatic acid phosphatase as a tumor marker. PSA has established utility immunohistochemically to confirm or refute the prostate as the site of origin for an undifferentiated neoplasm. It also is an excellent tool for monitoring patients after definitive therapy. The role of PSA in early detection of prostatic carcinoma and in staging of established neoplasm remains controversial. The salient features of PSA biochemistry and immunohistochemistry, the serum assays, and the relationship of the antigen to prostatic carcinoma and nonmalignant prostatic pathology are reviewed. The use of PSA in conjunction with other detection modalities such as prostatic ultrasound are discussed.