Cautions

This test result should not be the sole basis for diagnosis. Carcinoembryonic antigen (CEA) and other tumor markers are not specific for malignancy and CEA testing has limited utility when used as the sole diagnostic test. Test results should always be correlated with cytology, imaging, and other clinical findings.

A low or negative CEA result may be misleading, as certain malignancies do not secrete CEA and will not produce elevated CEA concentrations in pleural effusions. Negative results should be interpreted with caution in patients who have, or are suspected of having, a non-CEA-secreting malignancy or who have cancer of unknown primary origin. Alternative methodologies, including cytology, imaging, and other tumor marker testing should be considered.

Carcinoembryonic antigen concentrations have been reported to be elevated in pleural fluid as a consequence of certain nonmalignant conditions, including liver cirrhosis, pancreatitis, complicated parapneumonic effusions and empyemas, and, rarely, tuberculosis. Results should be interpreted with caution in patients with those conditions.

In rare cases, some individuals can develop antibodies to mouse or other animal antibodies (often referred to as human anti-mouse antibodies [HAMA] or heterophile antibodies), which may cause interference in some immunoassays. Caution should be used in interpretation of results, and the laboratory should be alerted if the result does not correlate with the clinical presentation.