Prostate-Specific Antigen: a Review of Assay Techniques, Variability and Their Clinical Implications

Prostate-specific antigen (PSA) is used worldwide in the detection and management of prostate cancer. Its discovery revolutionised the care of patients with prostate cancer, but there remains a question of why inter-assay variability exists and how significantly this affects the decision-making process in the care of patients with the disease. We conducted a literature review to evaluate the two areas: inter-assay variability and its relation to clinical practice. Our results show there are internationally recognised standard assays, and the variability of assays are reliant on local/national calibration to a set standard preparation and rely on the measurement of different isoforms of PSA on an equimolar basis. Inter-assay variability exists and can be as high as 8%, which has differing impacts on decision making for diagnostic procedures and treatment modalities depending on the clinical circumstances and PSA level.