Lung cancer is known as ‘the first killer of cancer’, and its incidence and death have become the malignant tumor with the highest urban morbidity and mortality in China, which is a major disease that seriously affects the life and health of our people. Non-small cell lung cancer accounts for 85% of lung cancers, and the 5-year survival rate is only 15%. The 2-year survival rate of small cell lung cancer is only 1%. Since 70% of lung cancer patients are already in advanced local stage or distant metastasis (stage IIIb/IV) when they are diagnosed, they lose the best time for treatment, and their prognosis is often late when they are found to be poor. Most patients with lung cancer are in advanced stage and cannot be treated surgically. The main treatment purpose of this period is systemic treatment-based comprehensive treatment, and most lung cancer patients need chemotherapy. Most lung cancer patients need chemotherapy. Hu Mu, the Department of Thoracic Surgery of Xuanwu Hospital of Capital Medical University, is a method of treating the disease with chemically synthesized drugs. Chemotherapy is one of the main means of treating tumors and certain autoimmune diseases. It was discovered after World War I that mustard gas could kill white blood cells in general, and it was thought that mustard gas could also kill the mutated white blood cells that cause leukemia. Thus, mustard gas was used as a “cure” to kill mutated white blood cells and other cancer cells. However, during treatment, patients commonly experienced significant side effects such as nausea and vomiting, hair loss, fatigue, and infection, which caused discomfort and became a source of fear for oncology patients. With the emergence of new chemotherapeutic drugs, the development of adjuvant chemotherapeutic drugs and the further understanding of chemotherapeutic drugs by pharmaceutical workers, the toxic and side effects of chemotherapy for tumor patients have been significantly reduced compared with before, and the fear of chemotherapy for lung cancer patients has been gradually reduced to disappear. Chemotherapy for lung cancer is divided into radical chemotherapy, palliative chemotherapy, preoperative neoadjuvant chemotherapy, postoperative adjuvant chemotherapy, and thoracic and pericardial cavity chemotherapy. Do all lung cancer patients need or are all suitable for chemotherapy? When choosing chemotherapy regimens for advanced lung cancer, we must consider the following factors: 1) the type of pathology; 2) the patient’s physical status; 3) the underlying disease, such as patients with diabetes mellitus for paclitaxel requiring glucocorticoid prophylaxis for allergy, should be evaluated for good glycemic control; 4) the patient’s possible tolerance of toxic side effects, such as patients who cannot undergo central venous line placement, the use of vincristine has 5. economic situation. In addition, the alteration of some molecules on tumor cells may make chemotherapy drugs less effective in killing tumor cells. For example, it has been found that some genetic alterations make the detoxification of a certain drug affected, thus making its side effects significantly increased. Once the research data are further mature, we should also obtain as much information as possible on the detection of the above molecular markers when selecting chemotherapy regimens, and develop individualized regimens for each patient when selecting chemotherapy regimens to improve chemotherapeutic efficacy and minimize toxicity. In addition, not all lung cancer patients are suitable for chemotherapy. Contraindications to chemotherapy include the following common aspects: 1) lung cancer patients with KPS<60 or ECOG>2 should not undergo chemotherapy; 2) lung cancer patients with white blood cells less than 3.0×10^9/L, platelets less than 60×10^9/L and red blood cells less than 2×10^12/L should not undergo chemotherapy; 3) lung cancer patients with severe heart, liver and kidney dysfunction or with serious complications and Those with severe heart, liver and kidney dysfunction or serious complications and fever of infection and bleeding tendency should not be treated with chemotherapy; 4. Consideration should be given to drug reduction, drug discontinuation or drug change if the following conditions occur in chemotherapy: the lesion still progresses after 2 cycles of treatment or deteriorates again during the rest period of the chemotherapy cycle; when the adverse reaction of chemotherapy reaches grade 4 and poses obvious threat to the patient’s life; when serious complications occur. The most effective therapeutic drugs for NSCLC treatment are mainly platinum and some new drugs that have emerged in recent years. Stage I-IIIA NSCLC is mainly treated with surgery, chemotherapy is generally used as postoperative adjuvant therapy, and can also be used as preoperative therapy for stage IIIA patients, while stage IV patients are mainly treated with chemotherapy and can undergo local palliative radiotherapy. Although there are many effective chemotherapy regimens for NSCLC, the overall efficacy is not high, generally 20-40%, and fewer patients can achieve CR (complete remission) after chemotherapy for non-small cell lung cancer, so most of them cannot be cured by chemotherapy and need to be combined with other treatments such as radiotherapy and surgery. For small cell lung cancer, chemotherapy is the main treatment: for limited stage small cell lung cancer, the current best combination chemotherapy regimen can achieve an overall remission rate of 80-90%, a complete remission rate of 40%-50%, and a median survival of 20 months. Effective combination chemotherapy can improve patient median survival by 4-5 times compared to patients receiving no treatment. For extensive-stage small cell lung cancer, combination chemotherapy regimens are approximately 60% effective and have a median survival of 7-9 months, with lower efficiency and survival than patients with limited-stage small cell lung cancer. For patients receiving chemotherapy, besides the efficacy of chemotherapy is the most important concern, the toxic side effects brought by chemotherapy are the most important topic for patients. Chemotherapeutic drugs are mainly cytotoxic drugs, which not only kill tumor cells, but also damage normal human tissues and organs to a certain extent. For several chemotherapy drugs commonly used in clinical practice, cisplatin mainly shows gastrointestinal and nephrotoxicity, carboplatin mainly shows gastrointestinal and hematological toxicity, vincristine shows hematological toxicity, gastrointestinal reaction and phlebitis, paclitaxel shows allergic reaction and neuromuscular toxicity in addition to hematological toxicity, and gemcitabine shows less gastrointestinal reaction. The main categories are hematologic toxicity and non-hematologic toxicity. Hematologic toxicity is mainly manifested by bone marrow suppression: decrease in white blood cells, platelets and hemoglobin. Non-hematologic toxicity is mainly manifested in the following aspects: 1. Gastrointestinal reactions: nausea, vomiting, diarrhea, oral mucositis, diarrhea is the most common GI reaction in chemotherapy. 2. Pulmonary toxicity: the incidence is about 3%, with various clinical manifestations: often dry cough, dyspnea, fatigue, progressive aggravation of cyanosis, dyspnea at rest, hypoxemia and so on. Most of them are related to specific drugs such as bleomycin and methotrexate. 3. Cardiotoxicity: The main manifestations are myocardial ischemia, arrhythmia, pericarditis, etc. The chance of occurrence varies with different drugs. The common ones are anthracyclines (adriamycin, epi-amycin, etc.) and paclitaxel (paclitaxel, doxorubicin).4. Neurotoxicity: acute central toxicity can be manifested as meningitis, chronic with cerebral white matter lesions and memory loss; peripheral neurotoxicity can be manifested as peripheral nerves such as numbness, sensory disturbance, muscle pain, spasm, etc. in the extremities and around the mouth. Common drugs such as vincristine, paclitaxel, etc. How to minimize the damage of chemotherapy to the organism? This is the most important topic for oncologists, tumor patients and their families: 1. First of all, nutritional support therapy is the most important part: chemotherapy can lead to anorexia, nausea, vomiting, diarrhea and other gastrointestinal reactions, resulting in nutritional loss and insufficient supplementation. Reasonable diet is very important, to consume sufficient calories and protein, eat vitamin-rich vegetables and fruits, try to avoid taking stimulating food, eat less and more meals. 2, antiemetic treatment highly selective 5-hydroxytryptamine 3 receptor antagonists in the prevention and treatment of acute vomiting caused by chemotherapy program with high efficiency, well-tolerated and other characteristics, has become a common drug for the treatment of acute vomiting. For delayed vomiting, the combined application of gastrofacial and corticosteroids also has good effect. 3, colony-stimulating factor: absolute value of granulocyte count <500/u L is called granulocytopenia. In addition to increased complications, it can also cause delayed chemotherapy or lower dose of the substance, the latter two conditions are unfavorable for radical chemotherapy of lung cancer. Granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) are effective in reducing the duration of granulocytopenia. If there has been a single episode of febrile granulocytopenia; 4. Analgesic treatment for cancer pain is one of the symptoms that seriously affect the quality of life of cancer patients, and should be given full attention by cancer patients and their families, and medical workers, according to the principle of three-step analgesic treatment proposed by WHO, the use of aspirin, codeine, morphine and other drugs alone or in combination with other adjuvant drugs can help patients to relieve most of their pain. Most patients feel pain.5. Other: Dexamethasone, Benadryl can reduce tissue edema and allergic reactions. Drugs with high vascular irritation, such as vincristine and fluorouracil, can easily cause phlebitis, so a central venous line can be placed before infusion, and poor appetite during chemotherapy can be given to enhance appetite with methacholine. In conclusion, with the development of human genomics and pharmacology, the introduction of new drugs and the promotion of individual chemotherapy treatment mode, "chemotherapy" is no longer a synonym of fear for patients and their families, and the quality of life of tumor patients during chemotherapy is getting better and better, and the survival of lung cancer patients will also be gradually improved.