Clinically, chemotherapy drugs are often injected or taken orally into the blood circulation, and then act on all organs of the body to achieve the purpose of anti-tumor, that is, systemic chemotherapy. According to the purpose of treatment, lung cancer chemotherapy is divided into radical chemotherapy, palliative chemotherapy, neoadjuvant chemotherapy (performed before surgery to shrink the tumor and reduce the stage), adjuvant chemotherapy (postoperative chemotherapy) and so on. Surgery and radiotherapy are local treatments, but when lung cancer is diagnosed, some tumor cells may have already escaped to other parts of the body and have not yet formed lesions. The advantage of chemotherapy is that it is a systemic treatment, and the drugs can reach any part of the organism, thus killing these potential lesions. If patients belong to any of the following conditions, they need to receive chemotherapy: 1. adjuvant chemotherapy is recommended after complete resection of stage II lung cancer; 2. for resectable N2 locally advanced stage IIIA non-small cell lung cancer, the current treatment is neoadjuvant chemotherapy combined with surgical treatment or surgical treatment combined with chemotherapy; 3. for stage IV patients, chemotherapy is the main treatment. Not all patients with advanced stage are suitable for chemotherapy. For patients in poor health condition, systemic chemotherapy is not suitable. And for elderly (>75 years old) patients, it is more reasonable to choose single drug and chemotherapy drugs with less side effects. Patients with advanced disease may receive several different regimens of chemotherapy depending on the tumor control and progression. The choice of chemotherapy drugs should be based on the patient’s pathological histological type, physical condition, previous treatment and other factors. Generally, 4-6 cycles of platinum-containing two-drug regimens are chosen for the first chemotherapy, which is the current international standard treatment regimen, while single-drug chemotherapy is mostly chosen for the second-line chemotherapy. The choice of chemotherapy regimen should be decided by the chemotherapy specialist based on the patient’s systemic condition and tumor status. It should be noted that some adverse reactions will inevitably occur after receiving chemotherapy, including gastrointestinal reactions (e.g. nausea, vomiting), bone marrow suppression (e.g. leukopenia), hair loss, and damage to vital organs (e.g. abnormal liver function). Therefore, the patient’s cooperation is needed during chemotherapy, with relevant examinations and follow-ups as requested by the physician, in order to deal with possible adverse reactions in a timely manner and to avoid the development of serious or even life-threatening adverse reactions. Not every patient will have the above-mentioned reactions after chemotherapy, and different regimens and drugs cause different adverse reactions, and the appearance of adverse reactions after chemotherapy is not necessarily related to the efficacy of chemotherapy. Therefore, if patients experience intolerable adverse reactions, they should actively communicate with their doctors and change chemotherapy drugs if necessary, rather than just tolerating them or giving up other chemotherapy drugs because of fear.