Whether chemotherapy is required after lung cancer surgery, and whether chemotherapy is required for early stage lung cancer In daily work, the most common question asked by patients is, “Hello, Dr. Xie, I’m done with this surgery, do I need chemotherapy in the future” This question is easy to answer and difficult to answer. This question, which can only be answered by your primary surgeon, depends on the following questions: 1. If, the patient’s surgery is palliative and other metastatic lesions are found in the thorax intraoperatively, or there are residual lesions intraoperatively, or, there are tumors in other areas, then postoperative chemotherapy is definitely necessary. If it is radical surgery, whether chemotherapy is needed depends on the patient’s lung cancer stage as well as pathology report. (1) If the patient has early stage lung cancer, in situ cancer, microinvasive adenocarcinoma, or stage Ia lung cancer (for this, please refer to the introduction of lung cancer staging in my article), and the surgery is radical resection, in principle, chemotherapy is not necessary after surgery. However, if the patient is younger, or the pathological type belongs to those with higher malignancy (adenosquamous carcinoma, sarcomatoid carcinoma), or the pathology suggests active cell differentiation, or poor differentiation, or the pathology suggests tumor invasion of lymphatic vessels and microvessels, these patients have a high risk of recurrence, and whether chemotherapy should be given should be weighed by the patient’s attending physician and considered comprehensively. If the patient is older, has deviated lung function, poor postoperative recovery, or combined with cardiovascular and cerebrovascular complications, it is better to avoid chemotherapy. (2) If it is stage Ib lung cancer, chemotherapy may be beneficial to the patient. In principle, if the patient is relatively young and does not have serious impairment of other organ functions, chemotherapy can be considered. (3) If it is stage IIa, IIb, IIIa or IIIb In principle, chemotherapy or targeted therapy is required, unless there is liver or kidney failure. 3.The patient’s age If the patient is over 75 years old, the application of chemotherapy is generally not recommended. If the patient is around 70-74 years old, single agent chemotherapy with milder side effects can be considered. 4.Patient’s recovery after surgery If the patient has a good recovery after surgery, chemotherapy should be started about 3-5 weeks after surgery; if the patient has a poor recovery after surgery and there is bronchial fistula or other complications after surgery, it is recommended to delay chemotherapy. 5.The result of tumor gene test: whether there is EGFR mutation or ALK fusion The current study found that if the patient has EGFR mutation or ALK fusion, the effect of choosing the corresponding targeted drug therapy as targeted therapy after surgery may be better than that of chemotherapy alone. 6, the results of the patient’s own genetic testing: the expression level of certain patients’ own genes may affect the efficacy of chemotherapy drugs, and if there is the expression of certain genes, the efficacy of chemotherapy may be poor. For example, increased expression of the multidrug resistance gene (MDR1) and its encoding P-glycoprotein (P-gp), or increased expression of the multidrug resistance-associated protein (MRP) gene, or increased activity of the glutathione detoxification enzyme system, or altered expression of the cytoplasmic resistance factors ERCC1, β-tubulin Ⅲ, and RRM1 can lead to chemoresistance, and these patients have limited efficacy after chemotherapy. Patients and physicians should carefully consider whether to chemotherapy. 7. Results of genetic tests related to adverse reactions to chemotherapy: Some genes can indicate the risk of adverse reactions after chemotherapy. For example, GSTP1, RECQ1, CDA, COX2, etc. can predict the occurrence of severe hematotoxicity or severe gastrointestinal toxicity in patients after chemotherapy. 8.Patients’ own wishes and economic conditions If patients have limited economic conditions, early-stage lung cancer patients can give up chemotherapy and save money for other aspects that can improve the quality of life and soothe patients’ mood (such as more relaxing travel), which is also a good strategy.