Many patients with cancer undergo surgery to remove the primary tumor lesions, but after a period of time, unfortunate news still comes: metastases appear in the lymph nodes, liver and lungs. In this regard, patients and their family members will ask: Why metastasis still occurs after the cancerous mass is removed? Cancer metastasis refers to the process of malignant tumor spreading from the primary site to other organs in distant places. Cancer is so daunting and seriously threatens human life and health precisely because cancer cells can metastasize. It has been 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 lymphatic metastasis; ③ hematogenous 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 the surrounding lymph nodes are removed, cancer cells can metastasize before (or even earlier), during and after surgery. Therefore, the surgical removal of cancerous tumors is not the end of the story. At present, the treatment of cancer still commonly adopts a combination of surgery, chemotherapy, radiotherapy and Chinese herbal medicine. Surgery and radiotherapy have the nature of regional treatment, while chemotherapy is a systemic treatment, which has a certain killing effect on metastatic cancer cells, which enter the blood and lymphatic fluid. Therefore, patients who have undergone various radical surgeries should undergo radiotherapy, chemotherapy and regular physical examination according to specific conditions, focusing on the surgical resection site, liver, both lungs, head, bones, etc., to detect metastatic lesions as early as possible and take corresponding treatment measures.