[Diagnosis of prostate cancer by means of the ratio of prostate specific antigen/gamma-seminoprotein (P/S ratio)].

Prostate specific antigen (PSA) and gamma-seminoprotein (gamma-Sm) are revealed to be the same protein. However, the serum concentrations of PSA and gamma-Sm in the same samples are frequently different. We previously measured a ratio of serum PSA concentration and gamma-Sm concentration (P/S ratio), and evaluated its usefulness for diagnosis of prostate cancers. In this paper, we tried to determine the cutoff value which brings better efficiency and diagnose prostate cancer by means of P/S Ratio. Between April 1988 and September 1992, 221 men underwent prostatic biopsy and/or TUR-P, and were diagnosed pathologically. Of 221 patients, 130 were diagnosed as BPH, prostatis or normal prostate (no cancer; NC) and 91 were diagnosed as prostate cancer (CaP). 1) The mean +/- SD of P/S ratio in 130 patients with NC was 0.919 +/- 0.563. While, the mean +/- SDs of P/S ratio were 12.447 +/- 44.353 in 91 patients with CaP and 2.052 +/- 0.751 in 39 Cap patients with serum PSA level of < or = 10 ng/ml. The mean P/S Ratios in CaP patients with serum PSA of < or = 10 ng/ml as well as in all CaP patients were significantly higher than those in NC patients (p < 0.0001). 2) When the cutoff value of P/S Ratio was determined to be 1.45, the highest efficiency (= sensitivity x specificity divided by 100), 83.4, was obtained. The sensitivity and specificity were 91.2% and 91.5%, respectively as a cutoff value of 1.45.(ABSTRACT TRUNCATED AT 250 WORDS)