Decreased expression of E-cadherin+ refers to epithelial calcium adhesion protein in breast cancer, and its expression correlates with tumor aggressiveness, also suggesting possible ductal carcinoma. E-cadherin refers to epithelial calcium adhesion protein, which plays a role in mediating adhesion between homologous cells and between cells and extracellular matrix. Down-regulated or absent expression of E-cadherin is prevalent in breast cancer cells, resulting in loss of contact inhibition, unrestricted growth and easy shedding of tumor cells, and its low expression is associated with breast cancer development and infiltrative metastasis. Immunohistochemical staining of E-cadherin classified its expression degree as (-), (+), (++), (++), (++++), and generally (++) and (++++) were normal expression, while (-) and (+) belonged to reduced or absent expression. In addition, generally breast lobular carcinoma E-cadherin is negative, while ductal carcinoma E-cadherin is positive. Therefore, breast cancer E-cadherin+ is classified as reduced expression, indicating strong invasiveness, and suggesting that the pathologic type may be ductal carcinoma. Patients are advised to consult a specialist to choose the appropriate treatment plan based on the immunohistochemistry results.