
Carcinoembryonic antigen (CEA) is a glycoprotein normally found in embryonic entodermal epithelium.
Increased levels may be found in patients with primary colorectal cancer or other malignancies including medullary thyroid carcinoma and breast, gastrointestinal tract, liver, lung, ovarian, pancreatic, and prostatic cancers.
Serial monitoring of CEA should begin prior to therapy to verify post therapy decrease in concentration and to establish a baseline for evaluating possible recurrence. Levels generally return to normal within 1 to 4 months after removal of cancerous tissue.
Nonsmokers: < or =3.0 ng/mL
Some smokers may have elevated CEA, usually <5.0 ng/mL.
Serum markers are not specific for malignancy, and values may vary by method.