Carcinoembryonic antigen (CEA)

An acid glycoprotein in the periphery of tumor cell membrane which is released into surrounding body fluids.


An oncofetal antigen that is normally produced in the fetal GI tract and is present at low levels in healthy adults.

Increased serum CEA described in breast, colorectal, gastric, lungs, pancreatic, and ovarian malignancies, but can also be observed in benign conditions including inflammatory bowel disease, cigarette smoking, diverticulitis, pancreatitis, liver disease, and alcohol consumption.

Levels are elevated in cancers which include colon, breast, lung, ovary and pancreas.

Approximately 70% of colorectal tumors consist largely of CEA negative cell lines, and they are documented to have scarce or no CEA secretion (CEA negative tumors constitute 49 to 75% of colorectal cancers).

In patients with negative baseline CEA, serum CEA is insufficiently sensitive in recurrence surveillance after treatment to improve oncologic outcomes.

Elevated CEA levels can also occur in patients with any of the following:

Heterophilic antibodies

Gastrointestinal tract inflammatory disease-diverticulitis, pancreatitis.

Peptic ulcer disease

Benign lung disease

Nonthyroid malignancies (eg, lung cancer, colon cancer)

Cigarette smoking

Not proven to be useful in screening asymptomatic individuals because of its low sensitivity and specificity.

Usefulness largely confined to surveillance after colon and rectal cancer surgery to allow for early identification of recurrence.

Preoperative CEA levels above 5 ng/ml predict poor outcomes in patients who underwent curative resections for colon cancer.

Low postoperative CEA is also associated with better prognosis, regardless of preoperative levels.

Cochrane review meta-analysis of 23 studies found that poolrd sensitivity of CEA at detecting colon cancer recurrence was 71% and a pooled specificity was 88% when applying a threshold of 5 ng/mL.

Patients with non-small cell lung cancer (NSCLC) with elevated CEA more likely to be sensitive to gefitinib than patients with a normal CEA.

ASCO and the National Comprehensive Cancer Network recommend postoperative monitoring of CEA for colon cancer resection every 3-6 months for 5 to 6 years for patients with resected stage Ii and II colorectal cancers.

Colon cancer surveillance with CEA testing alone is not sufficient as 20-30% of patients do not have an elevation with cancer recurrence.

It has a weak roll in a screening tool for colorectal cancer but it has a prognostic biomarker as a surrogate of disease burden preoperatively for patients undergoing colon resection, as well as predictor of disease recurrence during follow up.

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