I. What is lung cancer chemotherapy Lung cancer chemotherapy, short for chemotherapy for lung cancer, is a treatment that uses chemical drugs to stop the proliferation, infiltration and metastasis of lung cancer cancer cells until the cancer cells are finally killed. It is a systemic treatment, and together with surgery and radiotherapy, it is one of the 3 major treatments for cancer.　　As the toxic effects of existing drugs can often continue for several weeks after discontinuation, each course of chemotherapy should be administered at intervals of 4 to 6 weeks from the date of starting chemotherapy, but the toxic effects of drugs must disappear before the next course of chemotherapy is administered. Special attention should be paid to the discontinuation or change of drugs in the course of chemotherapy. At present, chemotherapy for lung cancer generally cannot achieve radical cure, therefore, at certain stage of chemotherapy, it should be combined with surgery or radiation therapy when possible to enhance local or regional control of tumor. The number of courses should be increased according to the patient’s response and efficacy, and complete remission should be achieved as much as possible.