The usefulness of serum free/total PSA ratio for diagnosis of prostate cancer in abnormal total PSA screening Thai patients

Abstract

Two hundreds and thirty three patients were included to evaluate the diagnostic performances and cost-effectiveness of serum free/total PSA ratio for diagnosis of prostate cancer when used in combination with conventional screening tests, serum total PSA and digital rectal examination. The diagnostic performances; sensitivity, specificity, positive predictive value, negative predictive value, accuracy and likelihood ratio, with different cut-off values were evaluated. Decision tree and cost-effectiveness analysis were studied to determine the most appropriate cut-off value of serum free/total PSA ratio that should be used in prostate cancer diagnosis program. It could not be definitely concluded which was the most appropriate cut-off value of serum free/total PSA ratio as the indication to perform prostate biopsy in Thai patients with abnormal serum total PSA, but the potential cut-off candidates ranged from 0.15 to 0.28 (0.15, 0.18, 0.20, 0.25, 0.28) depending on the patient groups with different serum total PSA. The cost-effectiveness analysis could not show the clear benefit of serum free/total PSA ratio when performed in serial with serum total PSA over serum total PSA alone as indication for prostate biopsy. The urologists should weight between the differences in diagnostic performances, benefits and risks of performing serum free/total PSA ratio with different cut-off values to minimize unnecessary biopsy.