Serological screening for a mucine-like carcinoma-associated antigen (MCA) in patients with gastrointestinal tract malignancies.

Mouse monoclonal antibody b-12 identifies a high-molecular-mass glycoprotein antigen strongly expressed by breast carcinoma cells. Since immunohistochemical studies have also demonstrated some reactivity with other epithelial neoplasms, and since "mucine-like carcinoma-associated antigen" (MCA) has gained considerable interest as a tumor marker in breast cancer, we have investigated 34 patients with histologically proven advanced gastrointestinal malignancies for the presence of elevated MCA serum levels. Our data suggest that screening for and/or monitoring of MCA in these tumors is unlikely to have any practical clinical relevance. The possible role of MCA as a marker in tissue specimens for abortive adenomatous differentiation in gastrointestinal (and other) neoplasms, however, remains to be determined.