CA 549 as a Marker in Breast Cancer

CA 549 is one of several carcinoma associated mucin antigens proposed as a breast cancer tumor marker. In this study, the performance characteristics of the CA 549 assay were validated and the clinical utility of the test was compared with that of other breast cancer markers including CA 15-3, CA M26, CA M29 and carcinoembryonic antigen. The upper limit of normal was established as 15.5 U/ml based on data for 250 control subjects apparently free of disease. Overall, CA 549 had a low negative predictive value (0.51) due to a low sensitivity in the detection of early breast cancer. However, the test had a high positive predictive value (0.93) reflecting a high specificity for the disease. In 56 patients with advanced breast cancer, the sensitivity was 0.71 for CA 549 alone and 0.79-0.84 for CA 549 combined with any of the other markers studied.