The treatment of many solid tumors now increasingly emphasizes neoadjuvant chemotherapy, meaning chemotherapy before surgery to shrink or downgrade the tumor before surgery, often resulting in longer patient survival time and quality of life. For example, if the stage of gastrointestinal malignant tumor, breast cancer and lung cancer is locally advanced (large tumor infiltration, regional lymph node metastasis, etc.), 2 to 4 cycles of chemotherapy before surgery can be chosen to reduce the tumor scope or eliminate subclinical metastatic lesions before surgery, which is easy to remove the tumor cleanly and completely, and then combined with 2 to 4 cycles of adjuvant chemotherapy after surgery, patients can obtain longer survival time than 6 cycles of chemotherapy after surgery. The combination of 2 to 4 cycles of adjuvant chemotherapy after surgery can provide patients with longer survival time than 6 cycles of chemotherapy after surgery. For some tumors with extensive local infiltration, it is sometimes difficult to remove the tumor cleanly by direct surgery, which is called not achieving R0 resection, and it is difficult to eradicate the residual cancer cells by postoperative chemotherapy.