Positive e-cad indicates the presence of malignant tumors, such as prostate cancer and invasive ductal carcinoma of the breast. e-cad, or E-cadherin (CDH1), is an adhesion molecule for cell-to-cell connections. Loss of its function can cause disruption of cell-to-cell connections, leading to cell dispersion, peripheral infiltration, and metastasis, and it is mainly found in various types of epithelial cells. In normal cells, the expression of e-cad is stable, but in cancer cells, the expression is not so stable, therefore, various malignant tumor cells and metastasis can be analyzed and judged by the results of e-cad examination. Generally speaking, a positive e-cad result indicates that there may be tumors with a low degree of malignancy, such as prostate cancer, invasive ductal carcinoma of the breast, etc., and vice versa, it indicates that the malignancy of the tumor is relatively high. However, e-cad alone cannot diagnose the type of cancer, but needs to be combined with other tests to make a comprehensive judgment, therefore, patients are advised to go to the hospital for further examination in time and actively cooperate with the doctor’s arrangement.