Diagnostic Performance of the Free to Total PSA Ratio in the Detection of Prostate Cancer in Patients Over 50 Years of Age at the Brazzaville Hospital Center, Congo

Abstract

Objective: To evaluate the diagnostic performance of total PSA, free PSA and the ratio of free to total PSA in identifying prostate cancer. Patients and methods: This was a descriptive, cross-sectional study from March 2019 to November 2021. Blood samples were analysed by sandwich ELISA and the ratio of free to total PSA (f/tPSA) was calculated. Prostate biopsies underwent histological analysis and the WHO 2012 Gleason Differentiation Score grading system was used. Results: 54 patients were selected; after histological examination 26 (48.15%) had prostate cancer (PCa) and 28 (51.85%) had Benign Prostatic Hyperplasia (BPH) (P<0.001). The mean total PSA (tPSA) of patients with PCa (26.1 ± 32.8 ng/ml) was higher than that of patients with BPH (9.64 ± 6.72 ng/ml) (p=0.019). The mean f/tPSA ratio of patients with PCa (14.3 ± 16.3%) was significantly lower than those with BPH (21.8 ± 19.3%). Gleason score was poorly differentiated in patients with tPSA < 4ng/ml and > 10ng/ml in 11.5% and 26.9% respectively. 61.5% of patients with f/tPSA <15% had SG≤6, SG=7 and SG ≥8 in 12.5%, 37.5% and 50.0% respectively. AUC/ROC was significantly higher for f/tPSA ratio (AUC, 0.67; 95% CI, 0.52 to 0.81) than for tPSA (AUC, 0.62; 95% CI, 0.46 to 0.77) and fPSA (AUC, 0.49; 95% CI, 0.34 to 0.65). Conclusion: Early diagnosis of prostate cancer requires the contribution of different PSA derivatives and the use of cut-off values.