The tumor becomes smaller after chemotherapy of first-line regimen of small cell lung cancer, which indicates that chemotherapy drugs are effective in treating small cell lung cancer, and it is recommended to continue chemotherapy. Small cell lung cancer patients can choose chemotherapy drugs such as fluorouracil, vincristine, paclitaxel, cisplatin, etoposide, irinotecan and so on, which can kill tumor cells, inhibit the malignant proliferation of tumor cells, shrink the tumor foci, and then improve the quality of life of the patients and prolong their life span. First-line chemotherapy program for small cell lung cancer: etoposide + cisplatin/carboplatin, irinotecan + cisplatin/carboplatin Therefore, small cell lung cancer patients can continue chemotherapy when the tumor becomes small after chemotherapy, and the treatment needs to be standardized according to the doctor’s prescription.