The anastomotic leakage remains the major early complication after laparoscopic anterior resection(LAR) for medium & low rectal cancer. Pelvic floor reconstruction (PR) is a key step in various standard resections for open radical rectal cancer surgery, which was considered to be helpful for decreasing the rate of leakage. However, PR in endoscopic LAR surgery is not routine practice and remains controversial. The purpose of this study is to evaluate the efficacy of PR during LAR for mid/low rectal carcinoma, especially in preventing anastomotic leakage.

Eligible patients with rectal cancer will be randomly assigned to group with pelvic floor reconstruction(PR) versus group without pelvic floor reconstruction(NPR).

We want to investigate the rate of anastomotic leakage and re-operation between the two groups, some other relevant outcomes will be concerned all the same.

Inclusion Criteria:

1. patients with histologically proven rectal adenocarcinoma
2. tumor located in the middle and lower rectum and anastomosis under the peritoneal reflection
3. Tumor assessed as a depth of invasion that was confined to pT1-pT3, bN0-1M0 by ultrasound colonoscopy and/or pelvic MRI
4. Negative circumferential resection margin confirmed by MRI
5. Performance status (ECOG) 0~1
6. Written informed consent for participation in the trial

Exclusion Criteria:

1. History of accepting lower abdominal surgery.
2. More than one colorectal tumor
3. Patients with unresectable distant metastasis or multiple metastases
4. Received neoadjuvant radiotherapy before surgery
5. Signs of acute intestinal obstruction, bleeding or perforation needing emergency surgery
6. Patients and/or family members cannot understand and accept this study
7. Non-rectal adenocarcinoma was confirmed by postoperative pathological examination