If it is early stage colon cancer, chemotherapy is not needed after surgery; if it is middle stage colon cancer, chemotherapy is needed after surgery, the two cases are different. Early stage colon cancer means colon tumor is detected very early and in time, the tumor invades the mucosal layer or submucosal layer, and there is no metastasis of surrounding lymph nodes, so regular follow-up after surgery is not needed, and chemotherapy is not needed, and follow-up for 5 years can be done. For mid-stage colon cancer, chemotherapy is needed after surgery, because mid-stage colon cancer may have deeper invasion and larger tumor, or the tumor may have lymph node metastasis, and there may be cancer cells in other parts of the body, but they are not detected during the preoperative examination. Without chemotherapy, there is a possibility of tumor recurrence or metastasis after surgery, such as liver metastasis or lung metastasis, etc. It is recommended that chemotherapy is also needed.