The value of gamma-seminoprotein in combination with prostate specific antigen in detecting prostate cancer

Background: The present study was undertaken to investigate the value of ga mma-seminoprotein (gamma-Sm) and the gamma-Sm/prostate specific antigen (PS A) ratio in combination with serum PSA in detecting prostate cancer. Methods: Prostate specific antigen, gamma-Sm and the gamma-Sm/PSA ratio wer e evaluated in 112 patients with untreated prostate cancer and 90 patients without prostate cancer who had serum PSA and gamma-Sm levels above their r espective detection limits. Results: When data for all of the patients were analyzed, serum PSA and gam ma-Sm levels were significantly higher and the gamma-Sm/PSA ratio was signi ficantly lower in patients with prostate cancer than patients without prost ate cancer. The serum. PSA and gamma-Sm levels significantly increased and the gamma-Sm/PSA ratio significantly decreased with advancing clinical stag e in patients with prostate cancer. Among the patients with serum PSA level s ranging from 1.8 to 6 ng/mL, the gamma-Sm/PSA ratio was significantly low er (P < 0.05) and gamma-Sm levels were lower (P = 0.054) in the patients wi th prostate cancer than in those without prostate cancer, but serum PSA lev els were not significantly different (P = 0.53). A receiver operating chara cteristic (ROC) analysis demonstrated that the areas under the ROC curves w ere 0.54 for PSA, 0.65 for gamma-Sm and 0.69 for the gamma-Sm/PSA ratio for prediction of prostate cancer in the PSA range from 1.8 to 6 ng/mL, althou gh the ROC analysis suggested that the gamma-Sm/PSA ratio does not provide significant advantage over PSA in detecting prostate cancer when all of the patients were analyzed. Conclusions: These results suggest that the gamma-Sm/PSA ratio and gamma-Sm may facilitate differentiation between patients with and without prostate cancer who have intermediate PSA levels.