CD326, also known as EpCAM (Epithelial Cell Adhesion Molecule), is a transmembrane protein expressed in epithelial cells. It plays a role not only in normal epithelial cells, contributing to embryonic development and adult cell differentiation, but also in epithelial-derived cancer cells, significantly impacting tumor formation and spread. CD326 also plays a role in the tumor microenvironment, participating in interactions between tumor cells and stromal components, cell migration, cell differentiation, and signal transduction. In clinical applications, CD326 is considered a potential diagnostic and therapeutic target due to its expression in epithelial-derived malignant tumors. For example, CD326 can be used for the positive selection of viable epithelial tumor cells in the peripheral blood, bone marrow, lymphatic tissues, and serous effusions of cancer patients. Additionally, the expression levels of CD326 in certain tumor types are associated with advanced disease stages and poorer overall survival rates, indicating that it may be a potential prognostic biomarker.