Chemotherapy is a very common anti-tumor treatment method. It is definitely not possible to carry out chemotherapy once, if it is discontinued once, it is possible that only 70%-80% of cancer cells can be killed, and the remaining cancer cells will develop again within a certain period of time, so it is not very effective in controlling tumors. Chemotherapy needs to be administered according to a course of treatment, using 3-week regimen or 4-week regimen, that is, the interval of 3 weeks or 4 weeks before 2 courses of treatment is more often applied, so that the residual cancer cells in the body can be killed to the maximum. At least 4-6 courses of treatment are needed, mainly postoperative adjuvant chemotherapy. In the case of palliative chemotherapy for advanced tumors, 8-12 courses or more than 20 courses may be required. It needs to be seen according to the patient’s physical condition, and also the tumor development.