CA15.3, MCA, CAM26, CAM29 ARE MEMBERS OF A POLYMORPHIC FAMILY OF MUCIN-LIKE GLYCOPROTEINS

The monoclonal antibodies that define the tumor markers CA15.3, MCA, CAM26 and CAM29 were found to react with coexisting epitopes present on mucin-like glycoproteins. Despite their immunologic relationship, the markers showed distinct concentration levels in various body fluids. Particularly, MCA and CAM26 were high in urine and amniotic fluid. Sera collected from pregnant or lactating women and especially human milk samples contained considerable amounts of CAM29 and MCA, but comparably small quantities of CAM26 and CA15.3. The concentrations of CA15.3, MCA, CAM26 and CAM29 were correlated in serum samples from patients with metastatic breast cancer. The discrepancy between immunologic relationship and dissimilar biologic behavior could be explained by a limited coexistence of epitopes on subsets of heterogeneous polymorphic mucins. All mucin markers which were investigated showed improved sensitivity for metastatic breast cancer compared with the established marker CEA.