Tumor markers
Carcinoembryonic antigenCEA
Oncofetal glycoprotein; colorectal cancer surveillance.
Sample
Serum
Clinical reference range
— to 3 ng/mL
Non-smoker · Smoker: <5.0
Conv: —–3 ng/mL
Biology
What it measures
Cell-adhesion glycoprotein expressed on fetal gut and re-expressed in adenocarcinomas.
Clinical use
Why we order it
Postoperative CRC surveillance every 3–6 mo for 5 y. Rising CEA prompts imaging.
Differential
Causes of abnormal values
Causes of HIGH
- ↑Colorectal cancer
- ↑Other adenocarcinomas (lung, breast, pancreas, gastric)
- ↑Smoking
- ↑IBD
- ↑Cirrhosis
- ↑Pancreatitis
Pitfalls
Pre-analytic & interpretation traps
- !Not for screening; ~30% of early CRCs do not produce CEA.