MUC1 serum assays in breast cancer: tumor specificities and reference levels

The aim of the study was to establish reference ranges and to explore the tumor specificities of two automated assays for MUC1. Sera from 124 female blood donors, 144 patients with benign disease of the breast, 69 patients with stage I, 75 with stage II, 89 with stage III and 38 patients with stage IV breast cancer were analyzed for MUC1 levels using two automated immunometric assays employing assay antibody pairs Ma695/Ma552 and BC2/GP1.4, respectively. All subjects were female. The Ma695/Ma552 assay yielded means of 13.86 (SD 6.55) kU/l for blood donors, 15.98 (SD 8.31) kU/l for benign disease, 15.83 (SD 7.92) kU/l for stage I, 15.01 (SD 8.03) kU/l for stage II, 33.80 (SD 66.53) kU/l for stage III and 469.22 (SD 906.61) kU/l for stage IV breast cancer. The BC2/GP1.4 assay gave means of 12.00 (SD 6.41) kU/l for blood donors, 14.68 (SD 9.33) kU/l for benign disease, 14.13 (SD 8.12) kU/l for stage I, 12.10 (SD 6.61) kU/l for stage II, 19.80 (SD 29.05) kU/l for stage III and 191.04 (SD 527.16) kU/l for stage IV breast cancer. Patients with benign diseases of the breast had slightly higher values than female blood donors with both assays leading to correspondingly different reference ranges. The Ma695/Ma552 assay had higher specificity for tumor MUC1 than the BC2/GP1.4 assay for all stages, and the study thus confirms the differences in tumor specificity for MUC1 assays.