Optimal cutoff value of preoperative CEA and CA19-9 for prognostic significance in patients with stage II/III colon cancer.

Purpose: This unicentric, retrospective cohort study aimed to identify the optimal cutoff values of preoperative serum carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) for the prognosis in patients with stage II/III colon cancer.

Methods: After excluding 43 patients with CA19-9 levels < 0.2 U/mL, 588 were included. Receiver operating characteristic curves were constructed to determine the optimal cutoff values of CEA and CA 19-9 for disease relapse.

Results: The median CEA and CA19-9 values were 3.6 (interquartile range: 2.1-7.2 ng/mL) and 14.3 (interquartile range: 8.1-30.0) U/mL, respectively. The optimal cutoff values of CEA and CA19-9 were 5.4 ng/mL and 22.4 U/mL, respectively. A multivariate analysis of relapse-free survival (RFS) showed that cancer stage, CEA, and CA19-9 were significant independent factors. The RFS of patients with stages II and III colon cancer was significantly stratified by CEA (< 5.4/ ≥ 5.4 ng/mL) and CA19-9 (< 22.4/ ≥ 22.4 U/mL). Prognostication based on the reference values (< 5.0 ng/mL for CEA and < 37.0 U/mL for CA19-9) was less significant than that based on the optimal cutoff values. Both elevated CEA and CA19-9 had no value dependency on RFS: RFS curves were similar between extremely elevated CEA (≥ 54.0 ng/ml) and intermediate CEA (5.4-54.0 ng/ml) and between extremely elevated CA19-9 (≥ 224.0 U/ml) and intermediate CA19-9 (22.4-224.0 U/ml).

Conclusion: The optimal cutoff values of preoperative CEA and CA19-9 for RFS were 5.4 ng/ml and 22.4 U/mL, respectively, in patients with stages II and III colon cancer. Further relapse risk stratification is possible using these values.