Glycan Signatures as Diagnostic Biomarkers in Gastrointestinal and Hepatopancreatobiliary Cancers: Advances in Glycomics and Glycoproteomics

The issue of early cancer diagnosis today is characterized by late symptom manifestation, difficulties in timely performing diagnostic procedures, and a lack of biomarkers that fully meet the criteria for sensitivity and specificity. An expanded search for novel diagnostic methods currently shows promise regarding the use of altered protein glycosylation patterns. This assumption is grounded in the ability of post-translational modifications, including changes in glycoprotein profiles and glycan structures, to serve as a signal of alterations at the level of synthetic processes. Tumor-associated glycan structures are released into the bloodstream, creating an opportunity for their detection using minimally invasive diagnostic methods. This article summarizes current data on the use of glycan signatures as cancer biomarkers for gastrointestinal and hepatopancreatic systems. The study utilized methodological discoveries in the fields of glycoproteomics and glycomics as informational material, actively integrating modern branches of omics technologies. Mass spectrometry and analytical methods made it possible to identify the most informative glycoproteomic and glycan biomarkers, the diagnostic efficacy of which was evaluated on internal and external validation cohorts. Analysis of the obtained data was performed with consideration of the limitations of the included studies, including small sample sizes, cohort heterogeneity, and potential publication bias. To enhance informativeness by developing new validation panels for early cancer detection, research recommendations for conducting new prospective studies are provided at the end of the review.