The diagnostic accuracy of carcinoembryonic antigen to detect colorectal cancer recurrence - A systematic review

Introduction: Carcinoembryonic Antigen (CEA) has been used as a tumor marker in the follow-up of colorectal cancer for more than 40 years. Controversy exists regarding its diagnostic applicability due to a relatively low sensitivity and a questionable effect on mortality. The aim of this review was to assess the diagnostic accuracy of CEA in detecting recurrence after intended curative surgery for primary colorectal cancer. Methods: Systematic literature searches were performed in PubMed, EMBASE and Cochrane databases, and articles were chosen based on predefined inclusion criteria. Reference lists from included articles were manually searched for additional publications of relevance. Results: Forty-two original studies with generally representative populations and long follow-up were included. Data were reported on outcomes from 9,834 CEA tests during follow-up. Reporting on the reference standards used was not optimal. Sensitivity of CEA ranged from 17.4 % to 100 %, specificity ranged from 66.1 % to 98.4 %, positive predictive value ranged from 45.8 % to 95.2% and negative predictive value ranged from 74.5 % to 100 %. Conclusion: Results point toward a sensitivity of CEA ranging between 50 % and 80 %, and a specificity and negative predictive value above 80 %. Results on positive predictive value showed low reliability. Overall, CEA did not effectively detect treatable recurrences at an early stage, and a clinically relevant effect on patient mortality remains to be proven.