Unexplained increases in serum carcinoembryonic antigen levels in colorectal cancer patients during the postoperative follow-up period: an analysis of its incidence and longitudinal pattern

Abstract

Background

Carcinoembryonic antigen (CEA) monitoring facilitates the detection of recurrence in patients with colorectal cancer (CRC) after resection. False-positive CEA has been reported in CRC patients with certain comorbidities or smokers. However, limited information is currently available on the frequency of and changes in falsely elevated CEA levels in patients without these conditions.

Materials and methods

We retrospectively examined CRC patients who underwent surgical resection at our hospital between 2001 and 2017, had no recurrence for at least five years, and were free of known factors that may increase CEA. Postoperative CEA levels were retrieved until 2 years before the last contact. For comparison, we similarly selected patients who developed recurrence after resection of CRC during the same period, and CEA levels at initial presentation, at nadir, and at the time of recurrence were reviewed. The patterns of elevated CEA (>5 ng/ml) were classified as transient, repeated, or persistent based on longitudinal changes. The relationships between CEA and carbohydrate antigen 19-9, transaminases, creatinine, and C-reactive protein were examined.

Results

CEA elevation occurred in 90 (20%) out of 446 eligible patients without recurrence at least once during the mean postoperative period of 50.5 months, whereas CEA was >5 ng/ml in 117 (53%) of 221 patients when they developed recurrence. Twenty-seven patients without recurrence showed a transient elevation in CEA, 45 repeated elevations, and 18 a persistent elevation; the frequency of a high preoperative CEA level increased in this order. The majority (98%) of false elevations ranged between 5 and 15 ng/ml. CEA was not associated with other laboratory data.

Conclusions

Unexplained CEA elevations were observed in 20% of recurrence-free CRC patients after surgery, and were classified into three patterns based on longitudinal changes. A more detailed understanding of patient-specific fluctuations in CEA will prevent unnecessary imaging studies and reduce medical costs.

KEY MESSAGES

Limited information is currently available on the frequency of and changes in falsely elevated carcinoembryonic antigen (CEA) levels after surgery for colorectal cancer. Unexplained postoperative CEA elevations were detected in 20% of colorectal cancer patients. The patterns of these elevations were classified into transient, repeated, and persistent.

Keywords:

• Carcinoembryonic antigen
• colorectal cancer
• postoperative change
• false elevation

Acknowledgments

The authors would like to thank Medical English Service (Kyoto, Japan) for editing the manuscript.

Author contributions

Hiroaki Nozawa and Soishiro Ishihara built study design. Hiroaki Nozawa and Yumi Yokota contributed to data collection, and all authors were involved in the analyses of the data. All authors were involved in the surgical treatment and follow-up of patients. Hiroaki Nozawa wrote the manuscript. Yumi Yokota, Shigenobu Emoto, Yuicihiro Yokoyama, Kazuhito Sasaki, Koji Murono, Shinya Abe, Hirofumi Sonoda, Takahide Shinagawa, and Soshiro Ishihara reviewed and revised the manuscript. All authors participated in the final approval of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The datasets generated during and/or analyzed during the current study are available from the corresponding author upon reasonable request.

Additional information

Funding

None.