Colorectal cancer is a common malignancy, and surgical treatment remains the most important treatment for colorectal cancer. The surgical outcome of colorectal cancer has been greatly improved through the use of anastomoses and the continuous improvement of surgical methods. However, the improvement of rectal cancer treatment results solely through the improvement of surgical techniques has reached a bottleneck, and it is difficult to improve it to a greater extent. More and more studies suggest that only surgery-based comprehensive treatment can further improve the therapeutic effect. Comprehensive treatment of colorectal cancer includes surgery, radiotherapy, chemotherapy, biologically targeted therapy, Chinese medicine and other treatments. Today, we will focus on the surgical treatment of rectal cancer for you. Why the most effective treatment for colorectal cancer is surgical resection Surgical treatment is the most effective treatment for colorectal cancer and the only possible cure for colorectal cancer. For early and mid-stage colorectal cancer, radical surgery can completely remove the tumor, two parts of normal intestinal tubes together with the surrounding mesentery and lymph nodes in the mesentery, which can completely remove the tumor and achieve good treatment effect. Other treatment methods, whether radiotherapy, chemotherapy or targeted therapy, can only shrink the tumor and reduce the stage, but cannot completely destroy the tumor, so the treatment effect is poor. For advanced colorectal cancer, if the tumor can no longer be completely removed, palliative surgery such as enterostomy or intestinal short-circuit surgery can be performed to solve the symptoms of obstruction and improve the quality of life of patients. What are the surgical resection methods for colorectal cancer? There are many kinds of surgical methods for colorectal cancer treatment, which can be roughly divided into the following categories: 1. Local resection Local resection refers to the partial or total resection of the intestinal wall in the area where the tumor is located, with the cutting edge not less than 2cm from the tumor, without dealing with the lymph nodes in the mesentery. Local resection includes transanal local resection, transanal endoscopic minimally invasive surgery (TEM) and colonoscopic resection. It is only suitable for patients with stage T1 colorectal cancer or those who cannot tolerate radical surgery such as old and frail. Even for stage T1 colorectal cancer, there is still 3-5% possibility of lymph node metastasis, and the recurrence rate after surgery is high, so it should be used with caution. 2.Radical resection radical surgery means complete surgical removal of the tumor and regional lymph nodes around the intestinal canal where metastasis may occur. The resection scope includes a certain length of intestinal canal including the tumor, and generally requires that the upper and lower cut edges of the intestinal canal should not be less than 5.0cm from the tumor; for rectal cancer with lower location, the lower cut edge of more than 1-2cm can be regarded as the safe scope. The resection should also include the corresponding mesentery, and the upper and lower cut edges and circumferential cut edges should be free of cancer residue (as shown in the figure: specimens after radical resection of rectal cancer) 3. combined organ resection combined organ resection (also called extended radical resection), that is, on the basis of conventional radical resection, other organs invaded should be removed at the same time. It is suitable for patients whose colorectal cancer has invaded the adjacent organs, but still can be radically resected. 4.Palliative resection is suitable for patients with late stage of colorectal cancer, with invasion of surrounding organs, extensive lymph node metastasis, or with metastasis of liver, lung, bone, brain and other distant organs, which cannot be removed completely.