CA15-3, also known as glycoantigen 15-3, is elevated mainly due to malignant tumors and benign lesions, as follows: 1, malignant tumors: breast cancer may be elevated more, but if a single CA15-3 is high, it is not certain that it is breast cancer, such as malignant tumors of the chest, such as lung cancer, as well as esophageal cancer, gastric cancer and other malignant tumors of the digestive tract, which may also cause this indicator to be elevated. 2. benign lesions: benign lesions such as mastitis, breast cysts, etc. may also lead to high CA15-3. It is not possible to diagnose breast tumor or other tumors based on this indicator alone, but also combined with imaging examination. If an occupying lesion of the breast is found, further biopsy pathology is needed to confirm the diagnosis. Only pathological examination is the basis for diagnosis, other tumor markers, including CA15-3, are only a reference.