What does the Carcinoembryonic Antigen test measure?

Why is Carcinoembryonic Antigen measured?

CEA is principally used in the monitoring of colorectal cancer after treatment, where rising levels indicate recurrence or metastatic progression before imaging becomes positive. It is also elevated in other gastrointestinal malignancies, lung and breast cancers, and in benign conditions including inflammatory bowel disease, liver disease, and smoking. Because of poor specificity and sensitivity, CEA is not recommended as a screening or sole diagnostic test for cancer; instead it serves as an adjunct to imaging and histology in staging, prognosis, and post-treatment surveillance. The baseline pre-treatment value and the trend over time carry more weight than any single result.

Reference ranges

Standard reference

Non-smokers <3.0 ng/mL; smokers <5.0 ng/mL (varies by assay and laboratory).

Functional medicine optimal

Not applicable — CEA is a tumour marker rather than a physiological parameter, and 'optimal' is context-dependent. Persistently undetectable or very low values after curative resection are favourable; any sustained rise above the individual's post-treatment baseline warrants investigation.

Units

ng/mL, µg/L

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.