Recently, many patients mentioned their concerns about invasive tests or surgery when they visited the clinic. It is believed that the tumor growing there must not be moved, otherwise the tumor cells will “fly” (metastasis). Do tumors really fly? I would like to tell you first of all that correctly chosen, invasive tests or surgeries that meet the specifications usually do not cause metastasis. Sometimes there is a risk of metastasis, but it is a choice that weighs the pros and cons relative to the benefit the patient gets from the treatment. Imagine if the tumor is all immobilized and not intervened and allowed to develop from early to late stage, is it good for the patient? However, there are some quacks in the society who allow their imagination to mislead the process of medical treatment, delaying the patient’s condition and causing irreparable and serious consequences. Of course, at present, the overall cancer treatment effect is still poor, and there are cases of advanced tumor patients passing away soon after starting treatment. However, it is equally impossible to have a chance of cure if no treatment is given. At the current medical level, doctors can predict the outcome of treatment based on various tests such as early and late stage of the disease and genes before treatment. However, it is not yet possible to accurately determine which patient will have a good prognosis and which one will not. To know whether tumor cells will “fly” (metastasis), we should understand what is meant by tumor metastasis, and secondly, the mechanism of tumor metastasis and the factors related to metastasis. What does metastasis mean? Metastasis refers to the process of tumor cells from one organ growing in other organs. It includes lymphatic metastasis, which is transferring to distant lymph nodes via lymphatic tract, and hematogenous metastasis, which is transferring to other organs via blood vessels. Mechanism of tumor metastasis: Various malignant tumors, usually starting from very small solid tumors, may have tumor cells shed into lymphatic tracts or blood vessels (partially engulfed by phagocytes), but this is not really metastasis. These tumor cells must settle in lymphatic tissues or other organs like fertilized eggs and absorb nutrients to keep growing, which completes the metastasis. Usually the number and concentration of shed tumor cells in the lymphatic tract and blood vessels determine the size of the likelihood of bed-formation. The strength of the body’s immunity and the structural characteristics of the tissues determine whether they can easily grow and develop in the new organs. The easier it is to release a large number of shed cells and to grow tumors in new organs, the more malignant we will be. Conversely, the less malignant it is. Factors related to metastasis generally include: i. Primary tumor condition: 1. Cancer cell type: Different types, or even the same type with different genetic mutations, have very different treatment methods and prognosis. Small cell lung cancer is highly malignant, and it is often aggressive and has a high mortality rate. However, it is very sensitive to chemotherapy, and the first time to strengthen the control and reasonable response, it will soon turn to safety. So invasive examination to determine the type of cancer cells is very important. 2.Cancer stage: the more advanced the tumor is, the greater the number and concentration of shed tumor cells in lymphatic tract and blood vessels, and the stronger the metastasis is. 3.Locations where cancer cells grow: organs with rich blood supply, such as bones, liver, lungs and brain. The lesion at the lung gate, with obvious symptoms of coughing and wheezing, is rich in lymphatic blood and easy to metastasize. Second, the patient’s own physical condition: the basic state of the body: poor general condition, often with more tumor gene mutations, low immune function and high tumor malignancy, all may increase the chance of cancer metastasis. Factors affecting patients’ psychological condition: It is often said that one third of tumor patients die of disease, one third die of fear and one third die of treatment. It may be a bit exaggerated, but the psychological effect causes low immune function and affects the treatment result. 1, self-life attitude and emotional characteristics: situation of mental depression, with more life vices. 2, family and interpersonal relationships. 3.Self-value orientation: mental depression, 4.Cultural level 4.Condition factors: 1.Medical conditions, treatment and experience: Almost all cancers (including various stages and cell types) have the possibility to survive (we all have successful cases), but it often depends on whether the treatment is reasonable or not. For example, in surgery, violation of operation specification, failure to follow the tumor-free principle and excessive extrusion of tumor can cause metastasis. 2.Economic condition: Those with poor economic condition often can’t persist in treatment. The question of whether tumor cells will “fly” (metastasis) is more in the aspect of examination. Unreasonable invasive examination or surgery: for example, supraclavicular lymph node aspiration is not done, tracheoscopy is not done, but percutaneous lung aspiration is done, which can cause needle metastasis. In general, try to choose the way of biopsy directly from the surface of the tumor without going through other tissues of the body, and the method of fine needle puncture. These methods do not squeeze the tumor to cause metastasis and also minimize the possibility of needle tract implantation. As a result of tumor treatment, there is currently damage to the normal organs of the body. The diagnosis based on no pathological and cytological evidence is actually irresponsible to the patients. In the future, treatment will require more detailed genetic and other tests in addition to pathological and cytological information, which raises the need for invasive tests and surgery even more.