Conventional
tumor markers are unsuitable for detecting
carcinoma at an early stage and lack clinical efficacy and utility. In this study, we attempted to investigate the differences in serum metabolite profiles of
gastrointestinal cancers and healthy volunteers using a metabolomic approach and searched for sensitive and specific metabolomic
biomarker candidates. Human serum samples were obtained esophageal (n = 15), gastric (n = 11), and colorectal (n = 12)
cancer patients and healthy volunteers (n = 12). A model for evaluating metabolomic
biomarker candidates was constructed using multiple classification analysis, and the results were assessed with receiver operating characteristic curves. Among the 58 metabolites, the levels of nine, five and 12 metabolites were significantly changed in the esophageal, gastric and
colorectal cancer patients, respectively, compared with the healthy volunteers. Multiple classification analysis revealed that the variations in the levels of
malonic acid and
L-serine largely contributed to the separation of
esophageal cancer;
gastric cancer was characterized by changes in the levels of
3-hydroxypropionic acid and
pyruvic acid; and
L-alanine, glucuronoic
lactone and
L-glutamine contributed to the separation of
colorectal cancer. Our approach revealed that some metabolites are more sensitive for detecting
gastrointestinal cancer than conventional
biomarkers. Our study supports the potential of metabolomics as an early diagnostic tool for
cancer.