Diagnostic Accuracy of Elevated Serum Carcinoembryonic Antigen for Recurrence in Postoperative Stage II Colorectal Cancer Patients: Comparison With Stage III

Purpose: Elevated levels of serum carcinoembryonic antigen (CEA) following a curative resection of colorectal cancer (CRC) indicate recurrence; however, the levels of CEA may be elevated above the normal limit without recurrence. The aim of this study is to analyze the diagnostic accuracy of elevated serum CEA for predicting recurrence in postoperative stage II and stage III CRC patients. Methods: A total of 336 stage II and stage III CRC patients who underwent a curative resection between January 2005 and October 2009 were enrolled. Sensitivities, specificities, positive predictive values (PPVs), negative predictive values (NPVs), likelihood ratios and post-test probabilities of recurrence associated with elevated CEA were analyzed and compared. Results: The median follow-up duration was 45 months (36 to 134 months). Twenty-seven of 189 stage II patients (14.3%) and 52 of 147 stage III patients (35.4%) developed recurrence during the follow-up period. Sensitivities, specificities, PPVs, and NPVs of elevated CEA were 37.0%, 91.4%, 41.7%, and 89.7%, respectively, in stage II patients and 46.2%, 90.5%, 72.7%, and 75.4% in stage III patients. Post-test probabilities of recurrence associated with elevated CEA were 41.8% in stage II patients and 71.9% in stage III patients. Conclusion: The predictive performance of the probability of recurrence associated with elevated serum CEA after a curative resection in stage II CRC patients is lower than that in stage III CRC patients.