Published online Sep 7, 2019. doi: 10.3748/wjg.v25.i33.4945
Peer-review started: March 12, 2019
First decision: March 27, 2019
Revised: April 4, 2019
Accepted: May 18, 2019
Article in press: May 18, 2019
Published online: September 7, 2019
Processing time: 180 Days and 22.9 Hours
Carcinoembryonic antigen (CEA) is a commonly used biomarker in colorectal cancer. However, controversy exists regarding the insufficient prognostic value of preoperative serum CEA alone in rectal cancer. Here, we combined preoperative serum CEA and the maximum tumor diameter to correct the CEA level, which may better reflect the malignancy of rectal cancer.
To assess the prognostic impact of preoperative CEA/tumor size in rectal cancer.
We retrospectively reviewed 696 stage I to III rectal cancer patients who underwent curative tumor resection from 2007 to 2012. These patients were randomly divided into two cohorts for cross-validation: training cohort and validation cohort. The training cohort was used to generate an optimal cutoff point and the validation cohort was used to further validate the model. Maximally selected rank statistics were used to identify the optimum cutoff for CEA/tumor size. The Kaplan-Meier method and log-rank test were used to plot the survival curve and to compare the survival data. Univariate and multivariate Cox regression analyses were used to determine the prognostic value of CEA/tumor size. The primary and secondary outcomes were overall survival (OS) and disease-free survival (DFS), respectively.
In all, 556 patients who satisfied both the inclusion and exclusion criteria were included and randomly divided into the training cohort (2/3 of 556, n = 371) and the validation cohort (1/3 of 556, n = 185). The cutoff was 2.429 ng/mL per cm. Comparison of the baseline data showed that high CEA/tumor size was correlated with older age, high TNM stage, the presence of perineural invasion, high CEA, and high carbohydrate antigen 19-9 (CA 19-9). Kaplan-Meier curves showed a manifest reduction in 5-year OS (training cohort: 56.7% vs 81.1%, P < 0.001; validation cohort: 58.8% vs 85.6%, P < 0.001) and DFS (training cohort: 52.5% vs 71.9%, P = 0.02; validation cohort: 50.3% vs 79.3%, P = 0.002) in the high CEA/tumor size group compared with the low CEA/tumor size group. Univariate and multivariate analyses identified CEA/tumor size as an independent prognostic factor for OS (training cohort: hazard ratio (HR) = 2.18, 95% confidence interval (CI): 1.28-3.73, P = 0.004; validation cohort: HR = 4.83, 95%CI: 2.21-10.52, P < 0.001) as well as DFS (training cohort: HR = 1.47, 95%CI: 0.93-2.33, P = 0.096; validation cohort: HR = 2.61, 95%CI: 1.38-4.95, P = 0.003).
Preoperative CEA/tumor size is an independent prognostic factor for patients with stage I-III rectal cancer. Higher CEA/tumor size is associated with worse OS and DFS.
Core tip: This is a retrospective study that sought to evaluate the prognostic value of carcinoembryonic antigen (CEA)/tumor size in rectal cancer, which may better reflect the tumor malignancy. Maximally selected rank statistics identified an optimal cutoff point of 2.429 ng/mL per cm for CEA/tumor size. Kaplan-Meier curves showed a significant reduction in the 5-year overall survival and disease-free survival in the high CEA/tumor size group. Univariate and multivariate analyses identified CEA/tumor size as an independent prognostic factor for stage I to III rectal cancer.