Preoperative Carcinoembryonic Antigen as a Predictor of 5-Year Survival in Rectal Cancer: Proposing a New Prognostic Cutoff.

Purpose: Carcinoembryonic antigen (CEA) is an important prognostic factor for rectal cancer. This study aims to introduce a novel cutoff point for CEA within the normal range to improve prognosis prediction and enhance patient stratification in rectal cancer patients.

Methods: A total of 316 patients with stages I to III rectal cancer who underwent surgical tumor resection were enrolled. The Cox proportional hazards regression model was used to evaluate the impact of preoperative CEA level and other co-variates on overall survival (OS). The Youden Index method was used for CEA optimal cutoff estimation.

Results: The mean follow-up period was 46.47 months. In risk-adjusted Cox proportional analysis, higher preoperative CEA levels (HR 1.17, CI 1.131.21; P < 0.001), and T-stage were associated with poor OS. The mean preoperative CEA level was significantly higher in patients with positive lymphovascular invasion (LVI) and perineural invasion (PNI) (CI: 1.06-2.45 and 0.75-2.33, respectively, P < 0.001, t test). Pathologic complete response (pCR) occurred in 71 (22.4%) cases. Patients with pCR had lower levels of preoperative CEA than non-pCR group (P = 0.002, CEA-CEA =  - 1.3; t test). Using Youden Index, the estimated optimal CEA cutoff value for predicting OS was 2.8 ng/mL (sensitivity 90%; specificity 78.5%). Lower preoperative CEA levels predict higher pCR rates, aiding patient stratification and planning.

Conclusion: Preoperative CEA may play a role in the prediction of pCR in rectal cancer. Considering the CEA level of 2.8 ng/ml, as a newly defined cutoff point, patients with a worse prognosis can be identified prior to operation. PNI, along with LVI as independent predictors, may be contemplated as prognostic indicators to improve treatment strategies.