Diagnostic precision of carcinoembryonic antigen in the detection of recurrence of colorectal cancer.

INTRODUCTION The aim of the study was to evaluate the diagnostic precision of serum carcinoembryonic antigen (CEA) in the detection of local or distant recurrence following resectional surgery for colon and rectal cancer. METHODS Quantitative meta-analysis was performed on 20 studies, comparing serum CEA with radiological imaging and/or pathology in detecting colorectal cancer (CRC) recurrence in 4285 patients. The cut-off for a 'positive' CEA ranged from 3 to 15 ng/ml between the various studies. Sensitivity, specificity and diagnostic odds ratio (DOR) were calculated for each study. Summary receiver operating characteristic curves (SROC) and sub-group analysis were undertaken. RESULTS The overall sensitivity and specificity of CEA for detecting CRC recurrence was 0.64 (95% CI: 0.61-0.67) and 0.90 (95% CI: 0.89-0.91), respectively. The area under the SROC curve was 0.75 (SE=0.04) and the diagnostic odds ratio was 18.44 (95% CI: 11.94-28.49). A CEA cut-off of 5 ng/ml yielded a higher diagnostic odds ratio than a cut-off of 3 ng/ml (15.5 vs. 11.1). Using meta-regression analysis the optimum CEA cut-off point for the best combination of sensitivity and specificity was 2.2 ng/ml. On sub-group analysis high quality studies, and those involving > or =100 patients yielded a marginal improvement in the sensitivity and specificity with minimal change to the SROC. CONCLUSION Serum CEA is a test with high specificity but insufficient sensitivity for detecting CRC recurrence in isolation. A cut-off of 2.2 ng/ml may provide an ideal balance of sensitivity and specificity. It may be useful as a first-line surveillance investigation in patients during surgical follow-up based on serial CEA measurements using temporal trends in conjunction with clinical, radiological and/or histological confirmation.