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Ratio of gamma‐seminoprotein to prostate‐specific antigen for the detection of prostate cancer: Its discrimination power could be influenced by the assay methods of PSA and/or gamma‐seminoprotein
Author(s) -
Akino Hironobu,
Suzuki Yuji,
Oyama Nobuyuki,
Kanamaru Hiroshi,
Okada Kenichiro
Publication year - 1999
Publication title -
international journal of urology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 67
eISSN - 1442-2042
pISSN - 0919-8172
DOI - 10.1046/j.1442-2042.1999.00090.x
Subject(s) - medicine , prostate cancer , prostate specific antigen , receiver operating characteristic , prostate , urology , nuclear medicine , cancer
Background: The ratio of gamma‐seminoprotein (γ‐Sm) and prostate‐specific antigen (PSA) has been regarded as being superior over PSA alone as a discriminator between prostate cancer and benign prostatic diseases. In previous studies, PSA and γ‐Sm were measured by the Eiken kit and the old‐version or revised Chugai kit, respectively. We compared the power of γ‐Sm ratio with that of PSA alone when using Markit‐M PSA assay and the revised Chugai γ‐Sm assay.Methods: Fifty‐three patients with prostate cancer having no metastasis and 116 with benign prostatic diseases were enrolled in this study. Prostate‐specific antigen was measured by Markit‐M kit and γ‐Sm was measured by the revised Chugai kit. The discrimination power of γ‐Sm ratio and PSA alone was evaluated with receiver operating characteristic (ROC) curves. Comparisons between prostate cancer and benign diseases were performed with Mann–Whitney U ‐test and Fisher’s exact test.Results: The optimal cut‐off value was set at 3.1 ng/mL for PSA and 0.935 for γ‐Sm ratio. Sensitivity, specificity and positive predictive value of PSA alone were 81.1, 81.0 and 66.2%, respectively, while those of γ‐Sm ratio were 73.6, 90.5 and 78.0%, respectively. There was no statistical significance in each value between PSA and γ‐Sm ratio. Areas under the ROC curves of PSA and γ‐Sm ratio were 0.881 and 0.866, respectively ( P > 0.05).Conclusion: Contrary to the previous reports, γ‐Sm ratio and PSA were not different in the discrimination between prostate cancer and benign prostatic diseases, which suggested that the discrimination power of γ‐Sm ratio, and presumably that of the free PSA to total PSA ratio as well, could be considerably influenced by the assay kits for serum PSA and/or γ‐Sm (free PSA) used. Therefore, the clinical significance of γ‐Sm ratio should be evaluated for each PSA assay kit.