SERUM-TO-URINARY PROSTATE-SPECIFIC ANTIGEN RATIO - ITS IMPACT IN DISTINGUISHING PROSTATE-CANCER WHEN SERUM PROSTATE-SPECIFIC ANTIGEN LEVEL IS 4 TO 10 NG ML/

Purpose: Benign prostatic hyperplasia (BPH) was shown to be associated with high concentrations of urinary prostate specific antigen (PSA). We investigated the serum-to-urinary PSA ratio in patients undergoing prostate biopsy to assess its efficacy in enhancing serum PSA specific ity in the detection of prostate carcinoma. Materials and Methods: Fro m November 1995 through January 1996 consecutive patients undergoing p rostate biopsy were prospectively included in the study. Serum and uri ne PSA levels were measured at our laboratory with the Tandem-R dagger assay. Samples were drawn 24 hours before prostate biopsy and at a di stance from prostatic manipulation or ejaculation. Results: We studied 73 patients with BPH and 57 with prostate cancer. Differences between BPH and prostate cancer were statistically significant considering se rum PSA or serum-to-urinary PSA ratios. In the 50 patients with a seru m PSA of 4.0 to 10.0 ng./ml. (35 with BPH and 15 with prostate cancer) the differences between prostate cancer and BPH were still significan t only when considering serum-to-urinary PSA ratio. Receiver operating characteristic curves showed that serum-to-urinary PSA ratio was a be tter predictor of prostate cancer than serum PSA. Conclusions: Our res ults suggest that the serum-to-urinary PSA ratio may be useful in dist inguishing BPH from prostate cancer, particularly in the diagnostic gr ay zone of serum PSA between 4.0 and 10.0 ng./ml.