Chemotherapy is chemotherapy, which is a systemic treatment-based therapy and occupies a large proportion in the postoperative adjuvant treatment of malignant tumors. In addition, in some advanced malignant tumors, if surgery is not possible, palliative chemotherapy can also be considered. There are also some tumors that cannot be operated directly and need chemotherapy first to shrink the tumor and reduce the stage, which is called preoperative neoadjuvant chemotherapy. For advanced malignant tumors, single agent chemotherapy is also available. Chemotherapy may cause side effects, such as nausea, vomiting, and decrease in white blood cells, etc., which need to be treated with antiemetic and leukocyte-raising drugs. Chemotherapy is also divided into courses, and postoperative adjuvant chemotherapy is usually 4-6 courses.