Targeted LC-MS/MS-Based Serum Nucleoside Metabolomics for Early Detection and Biomarker Discovery in Colorectal Cancer.

Colorectal cancer (CRC) is a leading cause of cancer-related morbidity and mortality worldwide, and early detection remains essential for improving patient outcomes. This study evaluated the diagnostic potential of targeted serum nucleoside metabolomic profiling, alone and in combination with established tumor markers (CEA and CA19-9). Serum samples from 50 CRC patients and 25 healthy controls were analyzed using a validated LC-MS/MS platform. Sample preparation and analytical conditions were optimized using a design of experiment (DoE) approach. Multivariate analysis was performed using partial least squares-discriminant analysis (PLS-DA), and diagnostic performance was assessed using receiver operating characteristic (ROC) curve analysis. CRC patients showed increased purine metabolites and modified nucleosides (adenosine, inosine, xanthine, hypoxanthine, and N6-methyladenosine) and decreased cytidine and uridine (p < 0.01). The metabolomic panel showed strong discrimination (AUC = 0.91; sensitivity = 88%; specificity = 86%). Conventional markers showed moderate performance (CEA: AUC = 0.83; CA19-9: AUC = 0.79). Combined analysis improved performance (AUC = 0.95; sensitivity = 92%; specificity = 89%). Targeted serum nucleoside profiling enhances CRC detection and improves diagnostic accuracy when integrated with conventional tumor markers.