Clinical application of free/total PSA ratio in the diagnosis of prostate cancer in men over 50 years of age with total PSA levels of 2.0-25.0 ng ml^(−1) in Western China

The goal of this study was to investigate the clinical application of free/total prostate-specific antigen(F/T PSA)ratio,considering the new broad serum total PSA(T-PSA)“gray zone”of 2.0–25.0 ng ml^(−1)in differential diagnosis of prostate cancer(PCa)and benign prostate diseases(BPD)in men over 50 years in Western China.A total of 1655 patients were included,528 with PCa and 1127 with BPD.Serum T-PSA,free PSA(F-PSA),and F/T PSA ratio were analyzed.Receiver operating characteristic curves were used to assess the efficiency of PSA and F/T PSA ratio.There were 47.4%of cancer patients with T-PSA of 2.0–25.0 ng ml^(−1).When T-PSA was 2.0–4.0 ng ml^(−1),4.0–10.0 ng ml^(−1),and 10.0–25.0 ng ml^(−1),the area under the curve(AUC)of F/T PSA ratio was 0.749,0.769,and 0.761,respectively.The best AUC of F/T PSA ratio was 0.811 when T-PSA was 2.0–25.0 ng ml^(−1),with a specificity of 0.732,a sensitivity of 0.788,and an optimal cutoff value of 15.5%.The AUC of F/T PSA ratio in different age groups(50–59 years,60–69 years,70–79 years,and≥80 years)was 0.767,0.806,0.815,and 0.833,respectively,and the best sensitivity(0.857)and specificity(0.802)were observed in patients over 80 years.The T-PSA trend was in accordance with the Gleason score,tumor node metastasis(TNM)stage,and American Joint Committee on Cancer prognosis group.Therefore,the F/T PSA ratio can facilitate the differential diagnosis of PCa and BPD in the broad T-PSA“gray zone”.Serum T-PSA can be a Gleason score and prognostic indicator.