Does serum carcinoembryonic antigen elevation in patients with postoperative stage II colorectal cancer indicate recurrence? Comparison with stage III

Abstract

Background and objectives: The aim of this study was to determine the accuracy of postoperative monitoring of serum carcinoembryonic antigen (CEA) to detect or rule out recurrence in patients with stage II colorectal cancer (CRC) by comparing results with stage III.

Methods: A total of 303 patients with CRC who underwent curative surgery were enrolled. Serum CEA was assayed, and radiological examination was performed routinely for 5 years after surgery. Yearly recurrence rates, sensitivities, specificities, likelihood ratios, and posttest probabilities were calculated.

Results: Sensitivity and specificity of CEA monitoring in stage II patients are almost same as those in stage III. Whereas recurrences occurred early in stage III, they occurred almost as frequently in both early and late stage II. The obtained posttest probability of recurrence in stage II patients with CEA elevation was significantly lower (only 30% or less) than those in stage III (approximately 80%).

Conclusion: Elevation of CEA in patients with stage II CRC does not represent recurrence with high probability. One of the reasons for the unreliability of CEA monitoring was its high false-positive rate. Another tumor marker with a lower false-positive rate is necessary to follow-up stage II CRC patients.