Breast cancer is a malignant tumor. Benign lesions are not called breast cancer and most of them are called breast lumps or breast masses, which may be caused by breast fibroadenoma or breast hyperplasia. During the examination, it is determined that breast cancer is a malignant tumor. Malignant tumors have cancer cells inside and gradually increase in size over time. The tumor will metastasize, such as lymph node metastasis or bloodstream metastasis, etc. Lymph node metastasis is usually more common in axillary lymph nodes, subclavian lymph nodes and supraclavicular lymph nodes, and distant metastasis is more common in lung metastasis or bone metastasis. If the tumor is very late or the tumor is not operated, the long time will lead to systemic metastasis and nutritional dysfunction, malignancy and eventually to death.