The Role of Complexed Prostate-Specific Antigen in the Detection of Prostate Carcinoma

Abstract

Although PSA unquestionably impacted the early detection of prostate adenocarcinoma, specificity of the test remains a problem. This problem is especially evident in PSA range 4-10 ng/ml that is often called "grey zone". Numerous studies have shown that 25-30% of men have prostate cancer in this range (Obort, 2013). Several approaches have been suggested to improve the specificity of PSA testing in the early detection of prostate cancer. These included the use of serum PSA related to prostate gland volume (PSA density), longitudinal measurement of serum PSA values to develop the rate of increase in PSA per year (PSA velocity) and the application of age-adjusted PSA reference ranged. All these approaches had limited success (Hong, 2014). Alternately cPSA is emerging as an alternative approach to PSA testing. Most trials to date suggest that cPSA is significantly more specific than total PSA at all clinically relevant tPSA levels from 2 to 20 ng/ml (Parsons et al., 2004). Factors supporting the use of cPSA measurement in clinical settings include greater stability (regarding transportation and storage), longer half life and less day to day variation. Unlike free PSA, cPSA results will remain constant over time under normal sample handling (Nielsen et al., 2008). In conclusion, cPSA assay as a single test leads to improvement in both sensitivity and specificity. At the same time it offers an economic advantage due to the use of a single analyte instead of two or more. Also, it is possible to avoid the variability observed when different manufacturers' assays are used in the measurement of more than one analyte. The U.S. Food and Drug Administration, in 2000, approved the use of cPSA for prostate cancer early detection. Data presented by most studies shows that cPSA test overcomes many of the shortcomings of PSA test and offers physicians and patients a strong weapon in the fight against prostate cancer (Ozen et al., 2006).