Diagnostic efficacy of free prostate-specific antigen/total prostate-specific antigen ratio for the diagnosis of prostate cancer in low concentration (≤4 ng/ml) and intermediate levels of total prostate-specific antigen (4.01-10.0 ng/ml).

Abstract

Serum prostate-specific antigen (PSA) is a useful tumor biomarker for prostate cancer (PCa) diagnosis. In this study, I aimed to compare the free/total PSA (fPSA%) with PSA alone for their usefulness in diagnosis for PCa. The patients who underwent prostate biopsy between January 2010 and January 2015 were evaluated retrospectively. Data were expressed as a mean + standard error and P < 0.05 as considered with statistical significance (Med Calc 14.12-2014). The receiver operating characteristic curves were calculated to study the sensitivity and specificity of fPSA and PSA and compared to each other in different PSA levels. There were 1055 patients in the study. The mean age of the patients was 64.2 + 7.5 and 66.3 + 6.4 years in Groups 1 and 2. The mean PSA and free/total PSA of the patients was 2.79 + 1 ng/ml, 0.2 + 0.08 and 6.49 + 1.59 ng/ml and 0.19 + 0.09 in Groups 1 and 2, respectively. I found the optimal cutoff for fPSA% was ≤18 and ≤14 in Groups 1 and 2 with a sensitivity of 62-45% and specificity of 58-79%. There was a statistical significant difference for fPSA when comparing the area under curve in the PSA level of 4.01-10 ng/ml (P = 0.0009). In this study, serum fPSA% has advantages for diagnosis of PCa when comparing PSA alone in different levels of PSA. These advantages are significant in PSA level of 4.01-10 ng/ml.