False-positive Elevations in Carcinoembryonic Antigen Levels at a Health Screening Center

ABSTRACT

BACKGROUND: Although routine screening of carcinoembryonic antigen (CEA) is not recommended for the early diagnosis of colorectal cancers, CEA levels are frequently measured in practice and during opportunistic health screening programs. We evaluated the frequency of false-positive results according to CEA level at a health screening center. METHODS: The medical records of 25,786 participants who underwent a general health check-up and CEA testing at the Seoul National University Hospital Healthcare System Gangnam Center from March 2015 to February 2016 were reviewed. CEA levels were measured using the Architect i2000sr (Abbott Laboratories, USA). The cut-off level for elevated CEA was 5.0 ng/mL. RESULTS: Among 25,786 participants who underwent CEA screening, 597 (2.3%) had CEA levels >5.0 ng/mL. Among 597 participants with elevated CEA levels, 12 (2.0%) had actual malignancies with CEA levels of 8.3–155.3 ng/mL. Diabetes, smoking, chronic obstructive pulmonary disease, and colonic polyps were considered as causes of false elevation. The false-positive rates of CEA according to level were as follows 5.1–10.0 ng/mL, 99.5%; 10.1–15.0 ng/mL, 87.2%; 15.1–20.0 ng/mL, 100.0%; >20.0 ng/mL, 33.3%. A subsequent decrease in the CEA level after a 1-month follow-up was observed in 47.6% of all cases with elevated CEA levels. CONCLUSIONS: False elevation in CEA levels in the range of 5.0–20.0 ng/mL is common in patients who underwent testing at a health screening center. False-positive results above 20.0 ng/mL are less common. These data could provide a guide for the interpretation of elevated CEA level at a health screening center.