Serum-to-urinary prostate-specific antigen ratio: a potential means of distinguishing benign prostatic hyperplasia from prostate cancer.

Objective: High concentrations of serum prostate-specific antigen (PSA) may be associated with the presence of benign prostatic hyperplasia or prostatitis. We investigated the serum-to-urinary PSA ratio in patients with or without prostate cancer to assess its efficacy in enhancing serum PSA specificity.

Methods: Patients presenting abnormal findings in digital rectal examination or documented prostate carcinoma were prospectively included in the study. A control group, with no evidence of prostate disease, hospitalized in the same time interval was included. Serum and urine PSA levels were measured in our laboratory with the Tandem R assay (Hybritech). Samples were drawn twice at 2-month intervals (M1 and M3).

Results: Sixty-eight patients were included in the study divided into 27 cases of benign prostatic hyperplasia, 20 of prostate carcinoma, 10 of prostatitis and 11 patients in the control group. Serum and urine PSA levels were not correlated (r < or = 0.1). There was no significant difference in any group from M1 to M3 as regards urinary PSA (p > or = 0.15). Intergroup comparison showed significantly (p < or = 0.004) high urinary PSA (mean level +/- SEM 28.3 +/- 3.4 micrograms/mmol creatinine) only in the benign prostatic hyperplasia group, mean levels in the prostate carcinoma, prostatitis and control groups being 3.7 +/- 1.1, 11 +/- 2.9 and 5.2 +/- 0.9 micrograms/mmol creatinine, respectively. Differences in urinary PSA levels between the confined prostate carcinoma and benign prostatic hyperplasia groups (p = 0.0008) were further increased when considering the serum-to-urinary PSA ratio (p = 0.0003).

Conclusion: Our results suggest that the serum-to-urinary PSA ratio may be useful in distinguishing benign prostatic hyperplasia from prostate cancer.