Blood β-HCG was measured weekly during treatment. Chemotherapy-sensitive patients can generally see a decrease in blood β-HCG 12-14 days after the end of a course of chemotherapy, and a reduction in metastatic lesions can be seen on repeat chest radiographs. Effective chemotherapy is defined as a 1 log decrease in HCG level after one course of chemotherapy. Those found to be ineffective should change drugs early to avoid tumor drug resistance. After treatment, physical examination of tumor regression, disappearance of metastases and blood β-HCG measurement turning negative, once a week for more than 3 consecutive negative times, is regarded as the criterion of recent cure. Note: If HCG is stable for more than 3 consecutive weeks and does not drop or starts to rise again, or if HCG does not drop by 1 log within 18 days after the first chemotherapy, it means that chemotherapy is not sensitive. If two consecutive courses of chemotherapy are ineffective, the patient is considered resistant and needs to switch to a replacement intense chemotherapy regimen.