Free/total serum prostate-specific antigen ratio: how helpful is it in detecting prostate cancer?

Objective To determine whether the use of free/total (f/t) serum prostate specific antigen (PSA) ratio would help reduce the number of prostate biopsies performed without compromising the detection of prostate cancer, in the setting of a transrectal ultrasonography (TRUS) clinic. Patients and methods The study included 93 consecutive patients referred to the clinic for TRUS and biopsy, Serum samples were assessed for total PSA and free PSA, and the fit PSA ratio calculated; 70 biopsies were taken. Patients over the age of 70 years with TRUS findings consistent with benign prostatic hyperplasia and with PSA levels <10 ng/mL were not biopsied. Results Tumour was detected in 23 patients; receiver operating characteristic curves showed no advantage for the fit PSA ratio when compared with total PSA in detecting prostate cancer, If a fit PSA ratio of < 0.15 had been used to determine the necessity for biopsy in the group with a total PSA of 4-10 ng/mL, then two-thirds of all tumours would have been undetected. Conclusion The fit PSA ratio had no advantage over total PSA in improving specificity at a given sensitivity for detecting prostate cancer, Therefore, it cannot be recommended as a means of decreasing unnecessary biopsies in patients with a raised PSA level and/or an abnormal digital rectal examination. This applied particularly to the group of patients with a total PSA of 4-10 ng/mL.