Disappearance of cancer cells after chemotherapy is a phenomenon of improvement, indicating that the application of corresponding drugs has a good effect on tumor control, but still need to pay attention to close observation. Clinically, after the emergence of malignant tumors, no matter whether surgery is performed or not, a large proportion of patients need to be controlled by adjuvant chemotherapy, which is mainly aimed at further killing cancer cells to achieve the best therapeutic effect. The disappearance of cancer cells in the course of treatment is a phenomenon of improvement, which suggests that the drugs are more effective for the corresponding tumors, and will significantly improve the clinical cure rate. After regular application of chemotherapeutic drugs, the effect of killing cancer cells will be obvious. After that, it is necessary to regularly review the physical condition through imaging examination, blood sampling and clinical checkups, and deal with abnormalities in time to prevent delaying the condition.