Despite the rising incidence of malignant tumors, the overall treatment level and efficacy of tumors are also improving with the increase of treatment means and the updating of concepts. For example, more than 10 years ago, the 1-year survival rate of advanced non-small cell lung cancer patients was only 15%, but now, thanks to the progress of comprehensive tumor treatment, the 1-year survival rate of patients with this most common clinical tumor is more than 40%. In this regard, scientific prevention and control of complications play an important role. When do complications occur? The harm caused by tumor to human body not only refers to the tumor itself, but also covers complications. In terms of causes, complications are divided into two categories. One category is related to treatment, and the other category refers to those caused by tumor invasion or metastasis. In treatment: post-surgery pain, infection; chemotherapy-induced decrease in white blood cells and platelets, nausea and vomiting; radiotherapy-produced radiation damage, all of which are related to treatment, are called treatment-related complications. Bone metastasis, pleural and abdominal fluid, intestinal obstruction, cancerous fever and other complications are directly related to tumor progression, which are called tumor-related complications. Treatment-related complications are related to treatment, and with the end of treatment, some of them will disappear by themselves, and those that cannot disappear by themselves will be effectively controlled or relieved through treatment. Tumor-related complications mostly occur in middle and late-stage cancer patients. Whether or not complications occur is closely related to the tumor patient’s condition, the timing of treatment, and the doctor’s intervention. Some early-stage cancer patients can achieve good results and clinical cure through surgery alone without complications. However, some patients may have several complications at the same time or successively. How to choose the timing of intervention? The harm of tumor complications is mainly reflected in three aspects: firstly, it increases patients’ pain and affects their quality of life; secondly, it may hinder the treatment of the tumor itself; and thirdly, certain serious complications such as pulmonary embolism, severe infections and bleeding may even be life-threatening. On the basis of a complete examination and assessment of the cancer patient’s condition, an experienced doctor predicts whether the patient will develop complications, whether early intervention is needed, and how to intervene. Early intervention can make complications appear as little or as late as possible. Once complications arise, there are various means of intervention available. For example, the common complication of central lung cancer is obstructive pneumonia, if some effective measures are adopted in advance according to the specific condition, such as local radiotherapy, intervention and Chinese medicine treatment may effectively prevent or delay the patient from falling into respiratory distress. For patients with lung cancer combined with large amount of pleural fluid, the immediate solution is to drain the pleural fluid by puncture and then inhibit the production of pleural fluid by drugs. Through these interventions, which combine Chinese and Western medicine, the patient’s quality of life is improved and time is gained for treatment. The emergence of complications often interferes with the tumor treatment plan. When chemotherapy causes bone marrow suppression in a patient, chemotherapy should be temporarily interrupted before the blood cell indexes return to normal, but delaying chemotherapy may affect the previous treatment effect. Another example is that if radiotherapy process has caused radiation pneumonia, there is no doubt that radiotherapy must be suspended and priority must be given to the treatment of pneumonia. The treatment of the tumor itself should be considered after the disease has recovered.