Background: The carcinoembryonic antigen (CEA) "value" itself is often useless in patients with a normal CEA level at initial presentation and those with tumor-irrelevant elevated CEA. Although the unified marker using CEA has been desirable for recurrent tumor staging as well as for primary tumor staging, little is known concerning its relationship with the survival of patients with recurrent colorectal cancer in particular.
Methods: This retrospective historical study included patients who experienced disease relapse after curative surgery for stage I-III colorectal cancer between 2006 and 2018. A total of 129 patients with recurrent disease after curative surgery for colorectal cancer were included. We focused on the CEA "ratio" (CEA-R: the ratio of the CEA level at the time of recurrence to that measured 3 months before recurrence) and aimed to evaluate the correlation between CEA-R and survival in recurrent colorectal cancer.
Results: Patients with a high CEA-R (≥ 2) exhibited significantly worse 2 year survival than those with a low CEA-R (< 2) (88.1% vs. 44.9%, P < 0.001), irrespective of the CEA value before primary resection. Multivariate analyses demonstrated that the CEA-R (HR; 3.270, 95% CI 1.646-6.497, P = 0.001) was a significant prognostic factor.
Conclusion: The CEA-R is a potential marker stratifying the survival of patients with disease relapse who exhibit aggressive biology at recurrent disease foci. As a novel marker, the CEA-R would serve as a clinical guide for tailoring treatment strategies at the time of disease relapse in patients with colorectal cancer.
Keywords: Carcinoembryonic antigen ratio; Colorectal cancer; Recurrence.