In the recent years, there are several findings revealing that the alterations of glycosylation play important roles in progression of diseases besides liver cancer and autoimmune diseases. The significant alterations in the glycosylation of secreted glycoproteins included a reduction in core fucosylation, increased branching and increased sialylation, and modifications to the epigenetic machinery have a profound effect on the glycan structures generated by cells during ovarian cancer progression. The levels of corefucosylated biantennary glycans and a-2,3-linked sialic acids were significantly increased in prostate cancer. There was an increase of 40% in core fucosylation in the main sialylated biantennary glycans in the pancreatic cancer serum, which would be indicative of a subset of tumor-associated glycoforms. Recently, the function of core-fucosylation was reported to be associated with the function of EGFR. The binding of EGF to its receptor requires core fucosylation of N-glycans of EGFR. Decreased core-fucosylation in gastric cancer might be associated with lower core-fucosylation of EGFR, and thus with reduced activation of EGF-induced phosphorylation of the EGFR pathway. Up to now, the mechanism behind the alteration of fucosylation during gastric cancer development is not fully understood. As to the source of abnormal glycosyaltion found in sera, increasing evidences have shown that abnormal glycosylation do appear in circulation in addition to diseases of liver and B lymphocytes. Our study and the others revealed that malignant tissues at least partially contributed to glycosylation alterations in circulation.In addition, immunoglobulins, the major glycoproteins in circulation were found to be secreted from some tumor tissues and tumor cell lines. The malignant related IgG showed special glycosylation in structure and stimulated cell proliferation in a pattern similar to growth factors functionally. In brief, the exact mechanisms on the alteration of peripheral N-glycome in gastric cancer require further exploration to elucidate. There are some limitations of this study. First, LCA was used for core-fucosylation abundance analysis by lectin blot in this study. However LCA binds not only to fucose but also to mannose residues in N-glycans. Recently PhoSL, a lectin binds only to core a-1,6-fucosylated oligosaccharides reported by a Japanese group in 2012, shows more specific than LCA in core-fucosylation assessment. Unfortunately, the availability of PhoSL is limited and its feasibility in clinical application in limited. LCA is now still an alternative lectin widely used for detecting a-1,6-fucosyl-linked sugar chains.Second, although both tissue and serum studies revealed similar finding indicating the low core-fucosylation in gastric cancer, whether the alteration of N-glycomic corefucosylation was caused by tumor or tumor microenvironment was not fully addressed in this study.