In this relation, the carcino–embryonic antigen (CEA) [63, 64], which does not differ in highspecificity and is not revealed in the bodily fluids of a healthy human, is of great interest.Its appearance and accumulation in blood (more than 5 ng/ml) evidence the presence of almostany oncological disease in the organism, like neoplasias of the digestive tract and respiratorysystem or carcinoma of the breast, head, or neck [63].Like all the oncofetal antigens CEA is a complicated glycoprotein, the proteinpart of which plays the determinative role. This evidence concerns the gene CEACAM5 and breast carcinoma.