title: A new modification of the Chiron ACS assay for total prostate-specific antigen achieves equimolar response characteristics and improves the detection of prostate cancer.
abstract: Nonequimolar-response assays for prostate-specific antigen (PSA) are criticized for overestimating total PSA in some men without prostate cancer (PCA), and underestimating total PSA in some men with PCA. We recently studied three nonequimolar-response PSA assays that had undergone modifications. While two of the studied assays achieved equimolar-response characteristics with improved areas under receiver operating characteristic (ROC) curves (AUC), the modification of the Chiron ACS PSA assay (ACS PSA2, Chiron) failed to achieve this. Recently, the ACS assay underwent another modification (ACS PSA, Bayer), which we investigated. Sera from 305 men (155 without and 150 with PCA, PSA > or = 2 and < or = 30 microg/l, Tandem-E) were measured using both modifications of the ACS assay and equimolar-response reference methods (Tandem-R free and Tandem-E, Hybritech). Molar response relative to the reference method and clinical performance (comparison of AUCs) between the previous and new ACS assay modifications were studied. The new modification of the ACS assay (ACS PSA, Bayer) achieved equimolar-response characteristics but reported lower values (average 10%) than the Tandem-E assay. Compared to the previous modification (ACS PSA2, Chiron), a 3% improvement in AUC (p = 0.01) was found. Using results of the redesigned equimolar-response assay (ACS PSA, Bayer), we calculated that 6 of 155 men without PCA in this sample set could be spared unnecessary biopsy compared with the previous nonequimolar-response assay (ACS PSA2, Chiron) without missing additional PCA (90% sensitivity). These data provide additional evidence for clinical advantages of equimolar-response over nonequimolar-response PSA assay formats.
authors.affiliation: Department of Urology, University of Münster, Münster, Germany. oberpen@uni-muenster.de
authors.forename: Frank
authors.initials: F
authors.lastname: Oberpenning
authors.forename: Christoph
authors.initials: C
authors.lastname: Weining
authors.forename: Burkhard
authors.initials: B
authors.lastname: Brandt
authors.forename: Gabriela
authors.initials: G
authors.lastname: De Angelis
authors.forename: Achim
authors.initials: A
authors.lastname: Heinecke
authors.forename: Michael
authors.initials: M
authors.lastname: Hamm
authors.forename: Petra
authors.initials: P
authors.lastname: Stieber
authors.forename: Lothar
authors.initials: L
authors.lastname: Hertle
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Schmid
authors.forename: Axel
authors.initials: A
authors.lastname: Semjonow
mesh_terms: D016022:Case-Control Studies; D006801:Humans; D007118:Immunoassay / Q000379:methods* / Q000592:standards; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood*; D011470:Prostatic Hyperplasia / Q000097:blood / Q000175:diagnosis; D011471:Prostatic Neoplasms / Q000097:blood / Q000175:diagnosis*; D012680:Sensitivity and Specificity
chemical_list: D017430:Prostate-Specific Antigen