Analysis of unexplained carcinoembryonic antigen elevation after curative treatment of locally advanced rectal cancer
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To analyze the causes and patterns of unexplained carcinoembryonic antigen (CEA) elevation after curative treatment in locally advanced rectal cancer patients.
Among the 1309 locally advanced rectal cancer patients treated with curative resection and radiotherapy between January 2001 and June 2011, 325 patients who postoperatively developed abnormal CEA elevation were reviewed. The unexplained CEA elevation was defined as a CEA level higher than 5 ng/mL with no evidence of cancer recurrence at the time of elevation.
Of the 325 patients, 143 (44%) had unexplained CEA elevations. The causes were categorized as delayed recurrence (n = 29, 20%), non-colorectal malignancy (n = 10, 7%), and non-malignancy-related conditions (n = 104, 73%). Shorter intervals between treatment and the first CEA elevation, and a higher peak CEA level, were observed in the delayed recurrence group compared with the non-colorectal malignancy or non-malignancy-related group (intervals of 6.8 vs. 44.9 vs. 23.2 months, respectively, p = 0.002; and peak CEA levels of 9.9 vs. 7.1 vs. 6.2 ng/mL, respectively, p = 0.034). In patients who showed delayed recurrence, the interval between the first CEA elevation and diagnosis of recurrence was a median of 13.0 months (range 3.8–60.6 months). Smoking was the most common cause for non-malignancy-related conditions. The patterns of unexplained CEA elevations were defined as sporadic (n = 78, 55%), stationary (n = 37, 26%), and increasing (n = 28, 20%). The patterns were significantly different depending on the cause (p < 0.001).
Analysis of the patterns of unexplained CEA elevations is a reasonable approach to predict the cause of the cancer.
KeywordsRectal cancer Carcinoembryonic antigen Surveillance Smoking
This work was supported by a National Cancer Center Grant (NCC-1510160 & NCC-1610440).
SUL: Data curation, methodology, project administration, formal analysis, writing—original draft, and writing—review and editing. EJ: Data curation, methodology, project administration, formal analysis, writing—original draft, and writing. SUL and EJ contributed equally to this study. DYK: Responsible for overall content, conceptualization, formal analysis, funding acquisition, software, and writing—review and editing. THK: Writing, reading, supervision and approval of article. JYB: Writing, investigation, reading, and approval of article. YC: Writing, investigation, reading, and approval of article. HJC: Writing, investigation, reading, and approval of article. JHO: Writing, investigation, reading, and approval of article.
Compliance with ethical standards
Conflict of interest
All authors state that there are no conflicts of interest
The study was conducted in accordance with the ethical principles of the Declaration of Helsinki and the International Conference on Harmonization guideline E6: Good Clinical Practice.