Diagnostic value of combined serum CEA and CA19-9 in colorectal cancer A meta-analysis

Colorectal cancer (CRC) is a leading cause of cancer-related mortality worldwide, and early detection remains critical for improving patient outcomes. Serum tumor markers carcino-embryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) are widely used in CRC diagnosis, yet their individual performance is limited. This meta-analysis systematically evaluated the diagnostic performance of CEA, CA19-9, and their combination across 95 studies (22,821 subjects). The combined CEA+CA19-9 testing achieved a pooled sensitivity of 0.585, specificity of 0.877, and diagnostic odds ratio of 9.99-representing improvements of 74% and 138% over CEA and CA19-9 alone, respectively. The area under the summary receiver operating characteristic (SROC) curve reached 0.783 for combined testing. Clinical utility analyses using Fagan's nomogram and likelihood ratio scatterplots confirmed the superiority of the multi-marker strategy. These findings provide evidence-based support for implementing combined tumor marker testing in clinical CRC diagnosis.