ABSTRACT: Single-incision laparoscopic surgery (SILS) is an emerging minimally invasive surgery to reduce abdominal incisions. However, despite the increasing clinical application of SILS, no evidence from large-scale, randomized controlled trials is available for assessing the feasibility, short-term safety, oncological safety, and potential benefits of SILS compared with conventional laparoscopic surgery (CLS) for colorectal cancer.This is a single-center, open-label, noninferiority, randomized controlled trial. A total of 198 eligible patients will be randomly assigned to transumbilical single incision plus one port laparoscopic surgery (SILS plus one) group or to a CLS group at a 1:1 ratio. Patients ranging in age from 18 to 80 years with rectosigmoid cancer diagnosed as cT1-4aN0-2 M0 and a tumor size no larger than 5 cm are considered eligible. The primary endpoint is early morbidity, as evaluated by an independent investigator. Secondary outcomes include operative outcomes (operative time, estimated blood loss, and incision length), pathologic outcomes (tumor size, length of proximal and distal resection margins, and number of harvested lymph nodes), postoperative inflammatory and immune responses (white blood cells [WBC], neutrophil percentage [NE %], C-reactive protein [CRP], interleukin-6 [IL-6], and tumor necrosis factor-? [TNF-?]), postoperative recovery (time to first ambulation, flatus, liquid diet, soft diet, and duration of hospital stay), pain intensity, body image and cosmetic assessment, 3-year disease free survival (DFS), and 5-year overall survival (OS). Follow-up visits are scheduled for 1 and 3 months after surgery, then every 3 months for the first 2 years and every 6 months for the next 3 years.This trial will provide valuable clinical evidence for the objective assessment of the feasibility, safety, and potential benefits of SILS plus one compared with CLS for the radical resection of rectosigmoid cancer. The hypothesis is that SILS plus one is feasible for the radical resection of rectosigmoid cancer and offers short-term safety and long-term oncological safety comparable to that of CLS, and that SILS plus one offers better cosmetic results and faster convalescence compared to CLS.ClinicalTrials.gov: NCT02117557 (registered on 16 April 2014).