Galectin-3 is a member of the β-galactose binding lectin family with a molecular weight of 30 kDa which is a chimeric structure consisting of a β-galactoside binding protein and a laminin. The main role of Galectin-3 on the cell surface is related to the adhesion between similar cells. It is expressed in a variety of organs and tissues, including neutrophils and vascular endothelial cells, but it is obviously absent in normal hepatocytes. Galectin-3 can downregulate the expression of some cancers and breast cancer associated proteins, and promote tumor metastasis. It can be used as a reference index for the degree of tumor deterioration.