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)

Aim of Study: 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. Methods: 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. Results: 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). Conclusion: 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.