Preoperative neoadjuvant therapy has become the guideline-recommended standard treatment for patients with locally advanced or mid-to-low rectal cancer with suspected regional lymph node metastasis. However, preoperative neoadjuvant radiotherapy caused radiation damage to the pelvic bowel, resulting in varying degrees of edema, vascular stiffness, and insufficient blood supply. According to the traditional rectal cancer surgery, the proximal bowel resection only needs to be more than 10cm above the upper edge of the tumor. However, this range of resection cannot remove all the damaged proximal bowel, and using the damaged proximal bowel for anastomosis may lead to the risk of anastomotic-related complications (including anastomotic leakage, anastomotic stenosis, and anastomotic proximal bowel stiffness, etc.) also increased. Therefore, extended resection of the proximal bowel with splenic flexure mobilization and using healthy proximal bowel for anastomosis may help reduce the incidence of complications related to rectal anastomosis after neoadjuvant therapy.

Inclusion Criteria:

1. Patients with mid-low rectal cancer who received preoperative neoadjuvant therapy (tumor distance ≤12cm from the anus);
2. The preoperative local stage is cT3-4N0-2M0 or cT3-4N0-2M1 (M1 is limited to liver metastases that can be surgically removed at the same time)
3. Preoperative neoadjuvant therapy (long-course concurrent chemoradiation or TNT)
4. Aged between 18-75 years old;
5. ASA rating: 0-2
6. ECOG Score: 0-2
7. BMI 18-30 kg/m2;
8. Radical surgical resection is expected to be possible on the basis of preserving the anus;
9. Sign the informed consent document.

Exclusion Criteria:

1. History of other malignant tumors;
2. Emergency surgery patients;
3. Severe underlying diseases, unable to tolerate surgery;
4. Without informed consent.