Relation between ultrastructural presence of CEA using peroxidase-antiperoxidase (PAP) method and tissue and serum levels of CEA in patients with breast cancer.

Ultrastructural studies were performed to detect the presence of carcinoembryonic antigen (CEA) in breast cancer by peroxidase-antiperoxidase (PAP) method. The evidenced presence of CEA was compared with the serum and tissue concentrations. A correlation between the presence of CEA at the ultrastructural level and tissue concentration was observed but not with serum levels. These studies revealed positive immunocytochemical staining for CEA when antigen concentration was 700 ng/g tissue and the reaction was strongly positive when the concentration was greater than or equal to 2000 ng/g tissue.