The time required for a course of chemotherapy for lung cancer depends on the pathological type, chemotherapy regimen, and patient’s physical condition, and cannot be generalized. In case of non-small cell lung cancer, usually a double drug containing platinum, such as cisplatin combined with gemcitabine, paclitaxel, doxorubicin, vincristine, etc., is the main regimen, and usually 3 weeks is a course of treatment. In case of small cell lung cancer, the chemotherapy regimen is mostly cisplatin combined with etoposide or cisplatin combined with irinotecan, and the course of treatment is usually 3 weeks. The patient’s physical condition is also an important factor. If the patient is in poor health, has high side effects of chemotherapy, and has not recovered before the next course of treatment, the chemotherapy will be delayed and the course of treatment will be extended. The chemotherapy regimen and course of treatment are mainly decided by the doctor in charge. Patients can communicate with the doctor in charge to determine the exact timing of chemotherapy and follow the doctor’s instructions to implement chemotherapy.