Why does cancer metastasize?

Generally speaking, the metastasis of cancer cells can be divided into several stages: the first stage is called invasion. At this stage, the epithelial cells of cancer cells will loosen the connection between cancer cells, so that cancer cells can regain their freedom and move to other places. The second stage is called infiltration. Cancer cells enter the circulatory system through the endothelium of blood vessels or lymphatic vessels. The third stage is called extravasation. At this stage, survivors baptized by the circulatory system will pass through the endothelial cells of microvessels and reach other tissues. The final stage is that these cancer cells migrate to the new world, thrive in other tissues and form metastatic malignant tumors. The reason why cancer cells can metastasize may be that they wake up the genes that have been sleeping for a long time in the body and are responsible for the early development of embryos, thus starting the relevant procedures, thus gaining terrible metastatic ability. In the future, drugs may be developed to inhibit the expression of Twist and other genes and avoid tumor metastasis. Or by screening these genes, we can find the future trend of the tumor early and give corresponding treatment. Perhaps in the future, cancer will not be such a terrible scourge, but it may not become another chronic disease. Ways of cancer metastasis: Cancer cells are very greedy and will go to any possible place. There are three main ways: First, lymphatic metastasis is generally the earliest, so lymph node dissection should be carried out when tumor is removed; Radiotherapy not only irradiated the primary tumor focus, but also irradiated the surrounding lymph nodes. Lymphatic system is all over the body, which is the ideal first choice for cancer cell metastasis. Lymphatic metastasis often goes from near to far. For example, breast cancer first metastasized to the ipsilateral axillary lymph nodes, and then to the clavicle, axillary lymph nodes, and even the contralateral axillary lymph nodes. Second, cancer cells that directly invade blood vessels or enter blood vessels through lymphatic vessels will reach other parts such as lung, brain, liver and bone with blood flow. This is a blood transfer. Gastrointestinal cancer often metastasizes to liver and lung, breast cancer, renal cancer and osteosarcoma often metastasizes to lung, lung cancer easily metastasizes to brain, and prostate cancer easily metastasizes to bone. Chemotherapy is to prevent cancer cells from transferring through the blood and use drugs to eliminate cancer cells along the way. Third, there is another kind of transfer that is less, that is, planting transfer. Cancer cells fall off the tumor surface and fall into the chest cavity, abdominal cavity and cerebrospinal fluid, which will take root and sprout. It usually occurs in the lower part of these cavities, such as costal diaphragm angle, rectal bladder fossa, skull base and so on. At present, for patients with extensive metastasis of cancer cells, the best way is CTC cell immunotherapy, which can activate the whole immune system, control the occurrence and development of tumors, enhance the body's immunity, relieve patients' pain, improve appetite, improve the quality of life and maximize the survival time.