Implications of Prostate Specific Antigen and its Molecular Derivatives in the Management of Carcinoma Prostate

Carcinoma prostate is the second leading cause of cancer-related deaths in men. In clinical practice prostate, specific antigen (PSA) estimation has been the gold standard for determining the presence of prostate cancer (PCa). Its elevation may indicate the presence of prostate disease but not always prostatic carcinoma. Identification of disease-specific molecular derivatives is the rational approach to addressing the current clinical challenge of whom to biopsy, whom to offer interventional therapy, and to plan the therapeutic strategies. The normal serum level of PSA is between 1.0 and 4.0 ng/ml, in men. The measurable PSA found circulating in the blood exists in complexed (cPSA) or bound form and free form (fPSA). Development of new monoclonal antibodies specific for fPSA and cPSA has allowed more accurate measurement of different molecular forms of PSA and their ratio in serum. Food and drug administration (FDA) has approved the measurement of fPSA in the diagnostic gray zone of 4.0-10 ng/ml. It can also be used as a decision-making tool for repeat biopsy. Measuring the ratio of [-2] pro PSA to total PSA further improves the specificity since they are raised in PCas. Same is true for the ratio of intact to fPSA. Volume based parameters and PSA velocity are other parameters which further refines the decision-making exercise. The present study is a focused review of these parameters of PSA, their implications, limitations, and use in the management of carcinoma prostate.