Robotic rectal cancer resection with natural orifice extraction is a recently developed minimally invasive surgery for patients with rectal cancer. However, it's safety and feasibility remain undiscussed and controversial. This study reported the clinical outcomes and prognostic factors of robotic assisted rectal cancer resection alone vs. robotic rectal cancer resection with natural orifice extraction to discuss aforementioned question.

Robotic rectal cancer resection with natural orifice extraction is a recently developed minimally invasive surgery for patients with rectal cancer. However, it's safety and feasibility remain undiscussed and controversial. This study reported the clinical outcomes and prognostic factors of robotic assisted rectal cancer resection alone vs. robotic rectal cancer resection with natural orifice extraction to discuss aforementioned question. From January 2015 to November 2016, a consecutive wave of 49 patients underwent robotic rectal cancer resection with natural orifice extraction and 49 matched patients underwent conventional robotic assisted rectal cancer resection were systematically analyzed in this study.

Inclusion Criteria:

1. T stage 1-3;
2. aged between 18 to 75;
3. the tumor margin is at least 4 cm from the anus;
4. body mass index ≤30kg/m2;
5. no distant metastases； (6）tumor size≤5cm.

Exclusion Criteria:

1. emergency surgery for intestinal obstruction or massive bleeding;
2. history of abdominal or pelvic surgery.

From January 2015 to November 2016, a consecutive wave of patients with rectal cancer underwent conventional robotic assisted rectal cancer resection and robotic rectal cancer resection with natural orifice extraction were invited to participate in this study.