Effect of elevated CEA levels on the outcome of colorectal cancer patients with different histopathologic types:A SEER population-based study

Limited and contradictory evidence has been reported regarding the prognostic effects of carcinoembryonic antigen (CEA) on the prognosis and metastasis of classical adenocarcinoma (CA), mucinous adenocarcinoma (MA), and signet-ring cell carcinoma (SRCC) in colorectal cancer (CRC) patients. We investigated the associations between histological subtypes and preoperative serum CEA levels in determining the oncologic outcomes of CRC patients. A total of 47,692 patients with clearly diagnosed CRC were selected from the Surveillance, Epidemiology, and End Results (SEER) database and divided into two cohorts based on serum CEA levels: CEA-normal (C0) and CEA-elevated (C1). Chi-square analysis revealed a correlation between CEA levels and histological classification. We then included a newly defined interaction variable (H&CEA) in the Cox regression analysis, which demonstrated that this variable could serve as an independent prognostic factor (P < 0.001). CA, in the context of elevated serum CEA levels, differed from the other two histopathological types, showing unexpectedly higher risks for both overall survival (OS) (HR = 1.70, 95% CI = 1.65-1.75, P < 0.001) and cancer-specific survival (CSS) (HR = 1.78, 95% CI = 1.72-1.85, P < 0.001). Furthermore, elevated CEA levels significantly increased the proportion of liver metastases in the CA group (25.43% vs 3.95%, P < 0.001). The interaction variable H&CEA can be used as an independent prognostic factor for CRC and should be considered in the diagnosis of CRC and the development of personalized treatment plans. Additionally, in the context of elevated CEA levels, CA is associated with poor prognosis and increased liver metastases. This CRC subgroup warrants special clinical attention from oncologists.