Modular Robotic NOSES-II for Mid-Rectal Cancer: A Preliminary Feasibility Study of a Structured Surgical Procedure

Background and Objectives: Robotic-assisted natural orifice specimen extraction surgery (NOSES) is a minimally invasive approach for mid-rectal cancer, but it is technically complex and lacks a standardized operational framework. This study aimed to propose and preliminarily validate a structured modular robotic NOSES II surgical procedure for mid-rectal cancer. Methods: This was a retrospective observational study that consecutively enrolled 11 patients with mid-rectal cancer who underwent modular robotic NOSES-II surgery at our center between December 2024 and August 2025. All procedures were performed by the same surgical team strictly following the predefined six-module structured surgical protocol. Perioperative indicators, pathological outcomes, and patient-reported outcomes (PROs) at 4 to 8 months postoperatively were collected. Key techniques were analyzed via high-definition surgical videos. Results: All 11 procedures were completed successfully without conversion to open surgery. The mean operative time was 299.6 plus or minus 54.2 minutes, and the mean intraoperative blood loss was 94.1 plus or minus50.6 mL. The mean number of harvested lymph nodes was 17.4 plus or minus 8.4, with a 100% R0 resection rate. No severe complications (Clavien-Dindo grade [≥] III) occurred. The mean postoperative hospital stay was 8.2 plus or minus 1.5 days. Postoperative PROs indicated good defecatory function, urinary function, and overall quality of life. Conclusions: Preliminary findings demonstrate that the structured modular robotic NOSES-II procedure is safe and feasible for the treatment of mid-rectal cancer. This modular protocol provides a clear and reproducible technical framework for this complex procedure, and it is expected to achieve favorable functional preservation while ensuring oncological radicality.