Whether colorectal cancer patients need adjuvant chemotherapy after surgery still depends on the clinical stage of the tumor. Stage I: adjuvant chemotherapy is not required after surgery. Stage II: Whether adjuvant chemotherapy is needed after surgery is controversial, but some studies have shown that patients with stage II colorectal cancer with the following high-risk factors can benefit from chemotherapy: 1, T4 stage tumor; 2, poorly graded histology (grade 3/4 lesions); 3, lymphovascular/vascular infiltration; 4, nerve invasion; 5, intestinal obstruction; 6, local perforation; 7, positive or indeterminate surgical margins; 8, cleared lymph nodes Insufficient number (<12). Stage III: adjuvant chemotherapy is required after surgery. The chemotherapy regimen depends on the specific condition. Stage IV: palliative chemotherapy to control the tumor and prolong life.