Actual Contribution of Free to Total PSA Ratio in Prostate Diseases Differentiation.

OBJECTIVES: To determine significance and sensitivity of the Free to Total prostate specific antigen (PSA) ratio (%fPSA) in diagnosis of prostate cancer and to correlate its sensitivity and specificity with diagnosis.

METHODS: Research included 220 patients, who had indication for biopsy (Clinic for Urology, University Clinical Center Sarajevo).

RESULTS: Average age of patients was 64.6 ± 8.1 years. Kruskal Wallis test indicates that there is a significant difference in age in relation to the diagnosis (KW χ2 =12.508; p=0.006). The correlation between the %fPSA level and diagnosis is positive and statistically significant (r=0.211; p=0.002) in the sense that cancer patients have the lowest %fPSA. Analysis of the sensitivity at 95% specificity of %fPSA compared to particular diagnosis shows the highest sensitivity for prostate cancer - 20.61% (8.35-31.02) with statistically significant AUC p<0.05. Analysis of %fPSA test in detecting prostate cancer, at cut-off values ≤ 0.16, shows a sensitivity of 72.3% and specificity of 50.4 (at cut-off values <0.07, sensitivity is 8.4%, and specificity is 97.8%).

CONCLUSION: PSA is organ specific but not cancer specific marker, whose total value, as well as the %fPSA serve as a basis, with a digitorectal exam, in the detection of prostate cancer. By increasing the cut-off values sensitivity of %fPSA increases and specificity decreases. %fPSA has a relative importance in the detection of prostate cancer, and should not be used as a guideline, without prior clinical examination.