Persistent high levels of carcinoembryonic antigen after tumor resection are associated with poorer survival outcomes in patients with resected colon cancer.

Background: Interindividual survival and recurrence rates in cases of locoregional colon cancer following surgical resection are highly variable. The aim of the present study was to determine whether elevated pre-operative and post-operative CEA values are useful prognostic biomarkers for patients with stage I-III colon cancer who underwent surgery with curative intent.

Methods: We conducted a retrospective study in patients with histologically confirmed stage I-III primary colonic adenocarcinoma who underwent radical surgical resection at Mexico's National Cancer Institute, between January 2008 and January 2020. We determined pre-operative and post-operative CEA and analyzed the association of scores with poorer survival outcomes in patients with resected colon cancer, considering overall survival (OS) and disease-free survival (DFS).

Results: We included 640 patients with stage I-III colon cancer. Pre-operative CEA levels were in the normal range in 460 patients (group A) and above the reference value in the other 180. Of the latter, 134 presented normalized CEA levels after surgery, but 46 (group C) continued to show CEA levels above the reference values after surgery. Therefore, propensity score matching (PSM) was carried out to reduce the bias. Patients were adjusted at a 1:1:1 ratio with 46 in each group, to match the number in the smallest group. Median follow- up was 46.4 months (range, 4.9-147.4 months). Median DFS was significantly shorter in Group C: 55.5 months (95% CI 39.6-71.3) than in the other two groups [Group A: 77.1 months (95% CI 72.6-81.6). Group B: 75.7 months (95% CI 66.8-84.5) (p-value < 0.001)]. Overall survival was also significantly worse in group C [57.1 (95% CI 37.8-76.3) months] than in group A [82.8 (95% CI 78.6-86.9 months] and group B [87.1 (95% CI 79.6-94.5 months] (p-value = 0.002). To identify whether change in CEA levels operative and post-surgery was an independent prognostic factor for survival outcomes, a Cox proportional hazard model was applied. In multivariate analysis, change in CEA level was a statistically significant, independent prognostic factor for overall survival (p-value = 0.031).

Conclusions: When assessed collectively, pre-operative and post-operative CEA values are useful biomarkers for predicting survival outcomes in patients with resected colon cancer. Prognoses are worse for patients with elevated pre-operative and post-surgical CEA values, but similar in patients with normal post-surgical values, regardless of their pre-surgery values.