CLINICAL AND TECHNICAL EVALUATION OF ACS(TM)BR SERUM ASSAY OF MUC1 GENE-DERIVED GLYCOPROTEIN IN BREAST-CANCER, AND COMPARISON WITH CA-15-3 ASSAYS

The mucin glycoprotein-detecting assay CA 15-3 is a valuable tool for monitoring the course of disease in breast cancer patients. Assays of CA 15-3 are based on the use of two MAbs to polymorphic epithelial muc in (PEM). We evaluated the technical and clinical performance of the C hiron ACS(TM) BR, an automated competitive chemiluminescence assay usi ng a single MAb, B27.29, and compared the assay's results with those o f the Centocor CA 15-3 RIA, the Abbott IMx CA 15-3, and the Boehringer Mannheim Enzymun-Test CA 15-3. The study population consisted of 253 healthy women, 66 patients with benign breast disease, 168 breast canc er patients, and 76 patients with other carcinomas. In the technical e valuation, we assessed the precision and linearity on dilution of the ACS BR assay. Cutoff values (upper limits of values seen in healthy su bjects) were determined for all four assays. Agreement between the ass ays was studied by linear regression analysis. The ACS BR assay gave w ithin- and between-assay CVs of 2.2% and 3.9%, respectively. Three sam ples from healthy women gave discordant values by ACS BR and were not included in the calculations. All four assays exhibit a highly similar pattern when monitoring breast cancer disease; the closest agreement of values was obtained between ACS BR and Centocor CA 15-3. We conclud e that the ACS BR assay is a fast and reliable immunoassay for measuri ng PEM in serum. Although it detects a slightly different epitope on t he PEM molecule than is targeted in other assays, for cancer serum sam ples it agreed better with the original Centocor CA 15-3 assay than di d the other two CA 15-3 assays tested.