Prognostic Impact of the Postoperative Carcinoembryonic Antigen Level after Curative Resection of Locally Advanced Rectal Cancer.

OBJECTIVES

This study was conducted to investigate whether preoperative or postoperative carcinoembryonic antigen (CEA) with a new cut-off value is more optimal for predicting long-term outcomes in patients with Stage II/III rectal cancer, and to investigate the effectiveness of postoperative adjuvant chemotherapy (POAC) based on the CEA values.

METHODS

Serum CEA levels were measured preoperatively (pre-CEA) and postoperatively (post-CEA). The area under the receiver operating curve (AUROC) was used to determine a cut-off for CEA. The cut-off for CEA relative to recurrence-free survival (RFS) was established as that giving the highest AUROC. In comparison of superiority between pre- and post- CEA levels, Akaike's information criterion (AIC) was used in the Cox proportional-hazard regression model.

RESULTS

The subjects were 323 patients who underwent curative surgical treatment for Stage II/III rectal cancer. AIC values indicated that RFS was better stratified by a post-CEA level with a cut-off of 2.3 ng/ml compared with other classifications of pre- or post- CEA. In Stage III or high-risk Stage II cases, there was no effect of POAC on RFS in those with post-CEA <2.3 ng/ml (p=0.39), but in those with post-CEA ≥2.3 ng/ml there was a trend for better RFS in patients who received POAC compared to those without POAC (p=0.06).

CONCLUSIONS

Patients with post-CEA ≥2.3 ng/ml had worse long-term outcomes compared with those with post-CEA <2.3 ng/ml. Post-CEA with a cut-off of 2.3 ng/ml may be useful in determining the indication for POAC for in Stage III or high-risk Stage II cases.