CEA is expressed at low levels in normal tissues of epithelial origin in a polarized manner; found only at the luminal portion of the cell but not at the basolateral surface [3] . In contrast, expression of CEA is frequently high in carcinomas, including colon, pancreatic, gastric, esophageal, lung, breast, uterine, ovarian, and endometrial cancers [3] . Cancer cells not only lose polarized (luminal) expression of CEA, but actively cleave CEA from their surface by phospholipases, an action that results in serum concentrations of CEA that can approach 5 mg/mL [3, 4, 5] . Serum CEA levels may be monitored to detect a response to anticancer therapy, or disease recurrence in colorectal cancer [6] , and serves as a prognostic indicator in patients with gastrointestinal cancers, where elevated levels indicate a poor prognosis and correlate with reduced overall survival [7, 8, 9] .