The dose of chemotherapy drugs is selected according to the principles of evidence-based medicine, taking into account the general condition of the patient and the results of various laboratory tests. For elderly and frail patients, those who have received multiple courses of chemotherapy or radiotherapy, those with abnormal liver and kidney function, leukocytopenia, thrombocytopenia, significant anemia and malnutrition, and those with fever, infection or other complications, adjustment of chemotherapy drugs and drug doses should be considered (see Tables IV, V and VI). In the course of treatment, if frequent vomiting, affecting diet or electrolyte disorders, diarrhea more than 5 times a day or bloody diarrhea, more than 3 degrees of bone marrow suppression, myocardial injury, liver and kidney dysfunction, and chemical pneumonia appear, the drug dose should be adjusted or chemotherapy drugs should be changed in a timely manner. In case of serious complications such as DIC, vascular embolism, shock, gastrointestinal bleeding, perforation, coma, etc., stop chemotherapy immediately and carry out rescue treatment rapidly. For patients with no obvious adverse reactions in chemotherapy, the treatment effect will be evaluated after two cycles of chemotherapy for patients with objective evaluation indexes, and those who are effective will continue chemotherapy until the recognized number of cycles is completed, and those with progressive disease will have their chemotherapy regimen replaced. For chemotherapy sensitive treatment effect such as choriocapillary epithelial carcinoma, testicular seminoma, small cell lung cancer, acute lymphoblastic leukemia, etc., those who do not achieve CR in certain cycles of chemotherapy can also be considered to change the chemotherapy regimen. In adjuvant chemotherapy and palliative chemotherapy, the treatment should be stopped after reaching the prescribed cycle, and the cycle of chemotherapy should not be increased arbitrarily. For those who do not have obvious effect even after changing the regimen several times, or those who are old and frail and have difficulty in tolerating adverse reactions, chemotherapy should be stopped and comprehensive treatment or biological treatment, Chinese herbal medicine treatment and best supportive treatment should be considered.