Development of an ELISA for sPSP94 and utility of the sPSP94/sPSA ratio as a diagnostic indicator to differentiate between benign prostatic hyperplasia and prostate cancer.

Abstract Background The serum PSA (sPSA) test has low specificity for prostate cancer (PCa), since sPSA also rises in benign prostatic hyperplasia (BPH). Serum PSP94 (sPSP94), a major secreted prostate protein, is indicated as a PCa marker. The potential of sPSP94 and sPSA in conjunction with each other to improve specificity of diagnostic test for PCa needs to be evaluated. Methods PCa patients (n = 33), BPH patients (n = 44) and healthy controls (n = 50) were recruited. A serum-based sandwich ELISA was developed to measure sPSP94 concentrations. Utility of sPSP94 in improving specificity of sPSA test was evaluated by studying sPSP94/sPSA ratios of study participants. Results Considerable decrease in overlap among sPSP94/sPSA ratio values of BPH and PCa patients was observed, as compared to sPSP94 or sPSA alone. For differentiating between BPH and PCa patients, this ratio had a maximum area under the curve (AUC) of 0.859 ( P  = 0.0132) and had a comparable sensitivity (90.91%) to sPSA with an increased specificity of 70.45%. Further, decision curve analysis (DCA) showed that sPSP94/sPSA ratio had a superior net benefit in identifying PCa, in patients opting for biopsy. Conclusion The sPSP94/sPSA ratio can be a better differentiating marker between BPH and PCa, than sPSP94 or sPSA alone.