Basic study of CA549, a new tumor marker for breast cancer, and evaluation of its clinical usefulness

: We performed basic and clinical studies of IRMA kits for serum CA549 antigen and examined the immunological correlation between CA549 and CA15-3 antigens. Satisfactory results were obtained in the basic studies of CA549 assays, such as the reproducibility and the dilution test. Many patients with breast cancer had elevated serum CA549 concentrations and significant correlation was observed between serum CA549 and CA15-3 values. Anti-CA549 antibody completely inhibited the binding of 125I-labeled anti-CA15-3 antibody to its antigens. These results suggest that CA549 and CA15-3 antigens have similar immunological characteristics.