During surgery for rectal cancer, there is considerable controversy regarding the optimal level of ligation of the inferior mesenteric artery. Several studies have demonstrated the benefit of high ligation of the inferior mesenteric artery for the rectal cancer in order to achieve block dissection of lymph node metastases along the root of the inferior mesenteric artery. In contrast, other studies have shown a significant decrease in blood flow after inferior mesenteric artery clamping that may increase the risk of anastomotic ischemia and the long-term outcomes were not significantly different between high ligation of the inferior mesenteric artery and low ligation. So, a modified procedure was suggested to dissect fatty tissues and nodes in the angle between the inferior mesenteric artery and the left colic artery and the artery was ligated below the left colic artery. In the present clinical trial, the investigators perform laparoscopic surgery with this management strategy in rectal cancer. Thus, the goal of this study is to investigate the short-term and oncologic long-term outcomes associated with laparoscopic lymph node dissection around the inferior mesenteric artery with preservation of the left colic artery for rectal cancer.

During surgery for rectal cancer, there is considerable controversy regarding the optimal level of ligation of the inferior mesenteric artery.There has been a differentiation between a high versus low ligation of the inferior mesenteric artery related to whether or not the ligation is above (high ligation) or below (low ligation) the left colic artery. Several studies have demonstrated the benefit of high ligation of the inferior mesenteric artery for the rectal cancer in order to achieve block dissection of lymph node metastases along the root of the inferior mesenteric artery. Excision of the apical lymph node at the root of the inferior mesenteric artery is thought to be necessary for radical resection of rectal cancer because apical lymph node resection contributes to improve lymph node retrieval rates and the accuracy of tumour staging. In contrast, other studies have shown a significant decrease in blood flow after inferior mesenteric artery clamping that may increase the risk of anastomotic ischemia. Patients with high ligation of inferior mesenteric artery had a 3.8 times higher chance of leaking than those with low ligation. Several studies confirmed that the long-term outcomes were not significantly different between high ligation of the inferior mesenteric artery and low ligation. So, a modified procedure was suggested to dissect fatty tissues and nodes in the angle between the inferior mesenteric artery and left colic artery and the artery was ligated below the left colic artery, which represented a compromise between the high and low ligation. Recently, several studies have described laparoscopic lymph node dissection around the inferior mesenteric artery with preservation of the left colic artery for rectosigmoid colon cancer. However, there are a few reports that describe the clinical outcomes associated with this management strategy. Furthermore, the long-term outcomes for laparoscopic lymphadenectomy around the inferior mesenteric artery with rectal cancer have seldom been reported. In the present clinical trial, the investigators perform laparoscopic surgery with this management strategy in rectal cancer. Thus, the goal of this study is to investigate the short-term and oncologic long-term outcomes associated with laparoscopic lymph node dissection around the inferior mesenteric artery with preservation of the left colic artery for rectal cancer.

Inclusion Criteria:

1. pathological confirmed rectal adenocarcinoma
2. solitary radical resectable tumors
3. tumor located at 5-15cm from the anus

Exclusion Criteria:

1. recurrent cases
2. emergency including obstruction, bleeding or perforation
3. severe abdominal adhesions
4. severe malnutrition can not be improved before surgery
5. can not tolerate to surgery due to severe comorbidities of heart, lung, liver or kidney
6. refractory hypoproteinemia or diabetes mellitus
7. previous or concomitant other cancers
8. the patients performed APR or hartmann surgery