The term "sugar chain" refers to a compound consists of various carbohydrates linked in chains by glycosidic bond. Familiar examples of sugar chains include amylose, which constitutes starch, and cellulose, which constitutes the cell wall of plants. Glycosylation is a common feature of changing of cancer cells, and some types of sugar chain structure is recognized as cancer development of markers specific for tumor markers can achieve the purpose of early diagnosis of cancer often caused by altered glycosylation 0 malignant epithelial cells lining the digestive tract, the change is one of the main overexpression mucin (mucin) in the tumor, the other a change is incomplete mucin glycosylation.