CEA (Carcinoembryonic antigen) is a type of glycoprotein attached to the cell membrane via glycosylphosphatidylinositol (GPI) anchor and stands for a set of highly related substance implicated in cell adhesion. It belongs to the immunoglobulin superfamily (IgSF) and there are two immunoglobulin domains including an N-terminal domain of 108 amino acids homologous to IgV-like and six domains homologous to the IgC2-like. The CAE gene family in humans is clustered on chromosome 19q and comprises 29 genes, 18 of which are commonly found. CEA is generally expressed in gastrointestinal tissue during embryonic development, but produced in very small amounts after birth. The serum level of it is not raised unless certain cancers tested. The CEA has become one of the most widely used tumor markers in clinical diagnosis and its main application is in gastrointestinal cancers, particularly in colorectal malignancy. Diethylenetriaminepentaacetic acid (DTPA), also known as pentetic acid, is a polyaminopolycarboxylic acid chelator composed of a diethylenetriamine backbone with five carboxymethyl groups. The molecule is thought as an expanded version of EDTA for the similar usage. DTPA is a white, water-soluble solid and used as the calcium or zinc trisodium salt. DTPA is commonly used to bleach pulp in paper making. Additionally, DTPA can be used not only as an antidote but also predominantly used as a carrier for contrast media in medicine like radiopharmaceuticals and gadolinium.