Much has been achieved in the treatment of malignant tumors (hereinafter referred to as cancer), but on the whole, cures are still in the minority, and the final outcome for most patients is still not optimistic. Then, what are the specific dangers faced by cancer patients? Metastatic recurrence of cancer remains the greatest danger. 1999, Tubiana reported that 45% of cancer patients were cured. Much progress has been made over the past decade, with nearly 50% of cancer patients surviving for more than 5 years. Even for those who are disease-free for more than 5 years, about 10% will recur, meaning that more than half of all cancer patients are still incurable. Some dangers occur slowly and can be foreseen by patients, their families and doctors, who can take the necessary measures. Most of these patients, in a chronic process, last for several days, weeks, months or even years, with gradual failure of one or more important organs, such as heart, lungs, kidneys, liver, brain, etc., inability to eat for a long period of time, very poor nutrition, severe pain, shortness of breath or weak, people getting weaker and weaker and wasting away, and finally dying. For example, liver cancer appears liver failure, liver coma death. Or an uncontrollable infection of the lungs, digestive tract, or urinary tract that leads to death. Some dangers occur suddenly, lasting from a few minutes to a few hours, for which the family may not be at all prepared, and for which it is difficult for doctors to take effective measures to combat. Such as pulmonary embolism, which is a high incidence of cancer patients is very insidious but very dangerous complications, because the tumor or blood clots fall off the blockage of the pulmonary artery caused by the tumor, there may not be any signs beforehand, or some very atypical abnormality, once the occurrence of large-scale pulmonary embolism, fast a few minutes the patient is no longer, slow only a few days. According to statistics, pulmonary embolism deaths account for the second cause of death of all cancer patients, it is difficult to prevent, difficult to diagnose and difficult to treat. Unless the embolized pulmonary vessel is small and not very large. Another category of more common danger is hemorrhage, where cancer cells invade important blood vessels causing them to rupture and bleed so much that death from hemorrhagic shock or asphyxiation may occur within seconds to minutes if it progresses quickly, and there is no chance of resuscitation at all, even in the hospital. There are also some elderly, very weak or abnormal mentality of the patient, feeding, drinking water easily choking, or sputum stuck in the throat choking, but also often within a few minutes of death, patients, family members and medical staff to take extra precautions. Some patients suffer from other serious diseases, such as heart disease, stroke, organ failure, etc. These diseases are already dangerous and can suddenly worsen or attack, leading to death in a very short period of time. Although cancer is not the direct cause of death, cancer and these diseases often promote each other, work hand in hand, and accelerate each other’s death. Other conditions such as ruptured alveoli forming a pneumothorax, massive pleural fluid affecting respiratory function, pericardial effusion leading to pericardial tamponade, and cerebral edema leading to cerebral herniation can also be fatal within a short period of time (from minutes to days) and will not be repeated. In conclusion, the risks faced by cancer patients are many, great, and at any time. It is not necessary that only patients with advanced stages have the risk of death, but many early stage patients may also occur; not only the risk of cancer itself, but also other concomitant diseases; not only the risk of the progression of cancer, but also the way of treatment of cancer; and not only in the progression of the disease, but also in the remission period may also occur. It should be widely known and guarded against to minimize the occurrence of accidents.