Breast cancer is the most common malignant tumor in women, and most patients will develop distant metastasis of cancer cells in advanced stages. Cancer cells can metastasize along the lymphatic vessels from the primary focus to the ipsilateral axillary lymph nodes. Blockage of major lymphatic vessels can cause upper arm lymphatic return obstruction and cause upper limb edema. According to the TNM staging of malignancy developed and promulgated by the International Union Against Cancer organization, stage IV breast cancer will have distant metastasis. Most patients in stage II and stage III patients will have regional lymph node metastasis. Among them, supraclavicular lymph node metastasis is a distant metastasis, which can be secondary to axillary lymph node metastasis or caused directly from the primary site. Once the supraclavicular lymph nodes metastasize, cancer cells may invade the veins via the thoracic duct or the right cervical lymph nodes, causing hematologic metastasis. Cancer cells can also directly invade veins to cause distant metastasis, commonly in bone, lung and liver. The most common sites of bone metastasis are spine, pelvis and femur, which can cause pain or walking disorder; lung metastasis can cause cough, coughing blood and pleural effusion; lung metastasis can cause liver enlargement and jaundice. A few patients will also have axillary lymph node metastasis or other systemic bloodway metastasis before the primary focus is found. And for men, because male breast is smaller, tumor lymph node metastasis occurs earlier. For patients with lymphatic metastasis, such as stage IIB and IIIA, radical surgery is the mainstay, and adjuvant chemotherapy, endocrine therapy or radiotherapy is commonly used before surgery according to the condition, and adjuvant therapy is often applied after surgery. For stage IIIB and C patients with metastasis in ipsilateral lymph nodes or significant metastasis in internal breast lymph nodes, radiotherapy, chemotherapy, endocrine and radiation therapy are available. The rate of lymph node metastasis in all stages is only 40%-50%, so biopsy of the anterior lymph nodes can save the patient from unnecessary surgery, and the need to remove the axillary lymph nodes can be decided based on the biopsy results.