The metastasis of cancer cells may be due to the awakening of embryonic development-related transcription factors that are dormant in the body. In general, cancer cells metastasize in several stages: the first stage is called invasion, in which cancer epithelial cells loosen connections between cancer cells, allowing them to “regain their freedom” and move elsewhere. The second stage is called infiltration, in which cancer cells cross the endothelium of blood vessels or lymphatic vessels and enter the circulatory system. In the third stage, called extravasation, the survivors of the circulatory journey cross the endothelium of the microvasculature and reach other tissues. The final stage is the migration of these cancer cells to new lands, where they multiply and thrive in other tissues to form metastatic malignancies. Cancer cells may be able to metastasize because they awaken genes in the body that have been dormant for a long time and are responsible for the development of the early embryonic phenotype, thus initiating the relevant processes and thus acquiring the terrible ability to metastasize. In the future, it may be possible to develop drugs to inhibit the expression of genes like Twist to avoid tumor metastasis, or to screen for these genes to detect the future course of tumors at an early stage and provide appropriate treatment. Maybe in the future, cancer will not be such a terrible beast, but will become another chronic disease. Cancer cells are very “greedy” and will run to any place they may reach, and there are 3 main paths: 1. The lymphatic system is all around the body, which is the ideal and preferred channel for cancer cell metastasis. For example, breast cancer first metastasizes to the ipsilateral axillary lymph nodes, then to the supraclavicular and infraclavicular lymph nodes, and even to the contralateral axillary lymph nodes. Bloodstream metastasis Cancer cells that directly invade blood vessels or enter blood vessels through lymphatic vessels will follow blood flow to other parts such as lung, brain, liver and bone, which is bloodstream metastasis. Gastrointestinal cancer often metastasizes to liver and lung, breast cancer, kidney cancer and osteosarcoma often metastasize to lung, lung cancer easily metastasizes to brain and prostate cancer easily metastasizes to bone. Chemotherapy is to avoid metastasis of cancer cells through bloodstream, and to destroy cancer cells “along the way” with drugs. There is another kind of metastasis which is less common, that is, implantation metastasis. If cancer cells fall off the surface of the tumor and “fall” in the thoracic cavity, abdominal cavity and cerebrospinal cavity, they will “take root”. The place of occurrence is usually in the lower part of these cavities, such as the angle of rib diaphragm, rectal bladder fossa, skull base and so on. In fact, we can’t say that if we don’t eat anything, we won’t get cancer, or if we are exposed to anything, we will get cancer. No single factor has been found to be an inevitable factor to induce cancer. The most important thing to overcome cancer is early detection, and most early cancers can be cured. For this reason, we should, firstly, have regular medical checkups and, secondly, look for some symptoms that may be related to cancer if we are not feeling well, and not go to the doctor only when we feel pain.