Clinical Application of Free to Total PSA Ratio in Detection of Prostate Cancer in Korean Men : Lower Cut-off Value

Im, Young Jae; Hong, Sung Joon; Chung, Byung Ha

Abstract

Purpose
Whether the free to total prostate specific antigen (PSA) ratio (F/T PSA ratio) would enhance the detection of prostate cancer in Korean men with serum total PSA levels between 4 and 20ng/ml was evaluated.
Materials and Methods
A total of 240 consecutive patients whose serum PSA levels were between 4 and 20ng/mul were enrolled in our recent two-year study. All patients underwent ultrasound-guided transrectal biopsies of the prostate gland. The F/T PSA ratio was measured using the Roche immunoassay (Roche Diagnostics GmbH, Manheim, Germany).
Results
Of the 240 patients, 202 (84%) had a benign histology, while 38 (16%) had prostate cancer. The two patient groups were well matched for age. The mean F/T PSA ratio showed a statistically significant difference between the two groups: the benign histology group was 0.14 (0.04-0.37) and the prostate cancer group was 0.10 (0.08-0.20) (p<0.05). Out of the 183 patients in the group with PSA levels of 4-10ng/ml, the F/T PSA ratios were 0.14 and 0.11 in the benign histology (n=158) and prostate cancer (n=25) groups, respectively (p<0.05). From the 57 patients with the PSA level of 10-20ng/ml, the F/T PSA ratios were 0.14 and 0.10 in the benign histology (n=44) and prostate cancer (n=13) groups, respectively (p<0.05). Overall, when the cut-off value of the F/T PSA ratio was 0.10, the sensitivity and specificity were 75.0 and 76.5%, while for the a cut-off value of 0.15 they were 83.3 and 39.7%, respectively.
Conclusions
Our data demonstrated the usefulness of the free to total PSA ratio in distinguishing benign prostate disease and cancer disease, hence eliminating unnecessary biopsies. It is recommended that a cut-off value for the F/T PSA ratio (0.10) be applied to Korean men; this is lower than the value used in Western countries.