Whether to have 4 cycles of chemotherapy for small cell lung cancer or 6 cycles depends on the sensitivity of small cell lung cancer and the patient’s physical condition, as well as the stage of small cell lung cancer, that is, the size and lymph node metastasis. If the lesion is relatively small and there is no combined lymph node metastasis, 4 cycles of chemotherapy for small cell lung cancer is clinically acceptable. If the lesion is large and there are more lymph node metastases, small cell lung cancer usually requires 6 cycles of chemotherapy or even 8 cycles, after 6-8 cycles, the lung CT can be reviewed and if there are residual lesions, chemotherapy and radiotherapy can be used together. The main difference between 4 cycles of chemotherapy and 6 cycles of chemotherapy is the patient’s tolerance and the effect achieved after chemotherapy.