Test Catalog

Test ID: CEA    
Carcinoembryonic Antigen (CEA), Serum

Useful For Suggests clinical disorders or settings where the test may be helpful

Monitoring colorectal cancer and selected other cancers such as medullary thyroid carcinoma


May be useful in assessing the effectiveness of chemotherapy or radiation treatment


This test is not useful for screening the general population for undetected cancers.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

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.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

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.

Interpretation Provides information to assist in interpretation of the test results

Grossly elevated carcinoembryonic antigen (CEA) concentrations (>20 ng/mL) in a patient with compatible symptoms are strongly suggestive of the presence of cancer and suggest metastasis.


Most healthy subjects (97%) have values less than or equal to 3.0 ng/mL.


After removal of a colorectal tumor, the serum CEA concentration should return to normal by 6 weeks, unless there is residual tumor.


Increases in test values over time in a patient with a history of cancer suggest tumor recurrence.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

The concentration of carcinoembryonic antigen (CEA) in serum should not be used to screen asymptomatic individuals for neoplastic disease, and the diagnostic efficacy of CEA measurements in high-risk groups has not been established.


Single values of CEA are less informative than changes assessed over time.


CEA values are method-dependent; therefore, the same method should be used to serially monitor patients.


Do not interpret serum CEA levels as absolute evidence of the presence or the absence of malignant disease. Use serum CEA in conjunction with information from the clinical evaluation of the patient and other diagnostic procedures.


Some patients who have been exposed to animal antigens, either in the environment or as part of treatment or imaging procedures, may have circulating antianimal antibodies present. These antibodies may interfere with the assay reagents to produce unreliable results.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Sturgeon C: Tumor markers. In: Rifai N, Horvath AR, Wittwer CT, eds: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018:436-478

2. Locker, GY, Hamilton S, Harris J, et al: ASCO 2006 update of recommendations for the use of tumor markers in gastrointestinal cancer. J Clin Oncol. 2006;24:5313-5327

3. Moertel CG, Fleming TR, Macdonald JS, et al: An evaluation of the carcinoembryonic antigen (CEA) test for monitoring patients with resected colon cancer. JAMA. 1993;270:943-947