Many patients with cancer have undergone surgery to remove the primary tumor lesions, and even received radiation and chemotherapy, but after a period of time, there is still unfortunate news: metastases have appeared in the liver, lung and brain. In this regard, patients and their family members will ask: after removing the cancerous mass, why will it still metastasize? Wu Xianwen, Department of Oncology, Xiyuan Hospital, Chinese Academy of Traditional Chinese Medicine Cancer metastasis refers to the process of malignant tumor spreading from the primary site to other organs in the distant area. It is found that the steps of cancer metastasis are: 1) growth and enlargement of primary tumor; 2) invasion of surrounding tissues and penetration into lymphatic vessels and blood vessels; 3) formation of tumor clots in lymphatic vessels and blood vessels and running with lymphatic fluid and blood; 4) staying in lymphatic vessels or blood vessel walls of distant organs; 5) penetration of lymphatic vessels and blood vessel walls and invasion of surrounding tissues; 6) proliferation and growth of cancer cells here and formation of metastases. The ways of metastasis include: ① direct spread: the tumor invades the surrounding tissues or organs directly from the primary site; ② through lymphatic metastasis; ③ through bloodstream metastasis; ④ implantation metastasis: the shed cancer cells can adhere to other tissues and form implantation cancer nodules. After understanding the metastasis mode of cancer, the crux of the problem is very white. Although surgery is called “radical surgery”, it is a local treatment method, which means that although the primary cancer mass and surrounding lymph nodes are removed, cancer cells can metastasize before (or even earlier), during and after surgery. Surgical removal of cancerous tumors is not the end of the story. At present, the treatment of cancer still commonly adopts integrated treatment methods such as surgery, chemotherapy, radiotherapy and Chinese herbal medicine. Surgery and radiotherapy have the nature of regional treatment, while chemotherapy is a systemic treatment, which has certain killing effect on metastatic cancer cells, cancer cells that enter the blood and lymphatic fluid, but the side effects are large, and while killing cancer cells, the damage to normal cells is also very serious. The characteristics of TCM therapy, with mild medicinal properties, low side effects and suitable for long-term use, have been valued by global oncologists in recent years.