The metastatic route of invasive breast cancer mainly includes lymphatic metastasis and blood metastasis. Usually, the tumor first invades the surrounding tissues, then metastasizes to the lymphatic, as well as through the blood, and finally to the distant organs. However, there are many cases of invasive breast cancer that have metastasis to distant organs but not lymphatic metastasis at the time of metastasis detection, which is called jumping metastasis. Lymphatic metastases usually follow a certain sequence, more commonly, the cancer cells invade the ipsilateral axillary lymph nodes through the lymphatic vessels at the lateral border of the pectoralis major muscle, and metastasize to the subclavian lymph nodes, supraclavicular lymph nodes, and the lymphatic area of the venous angle. It can also metastasize to distant areas by invading the venous blood stream via the left or right lymphatic vessels of the thoracic duct. For breast cancer in the upper inner quadrant, the tumor can also metastasize to the parasternal lymph nodes, that is, to the lymph nodes surrounding the internal thoracic artery or the internal mammary artery. The skin of the chest wall has an extensive lymphatic network formed by microscopic lymphatic vessels. Breast cancer on one side can metastasize along the superficial lymphatic network of the skin to the contralateral breast and the contralateral axilla. The lymphatic fluid from the breast goes down through the deep surface of the rectus abdominis sheath and through the hepatic round ligament to the hilar and subphrenic. Patients with invasive breast cancer can also develop hematogenous metastasis, in which cancer cells can directly invade the blood circulation, i.e., flow back into the axillary vein, subclavian vein, and vena cava with the veins of the breast. After passing through the blood circulation, it can then metastasize to the liver, lung tissue, and even to the vertebral body.