This study was single-center retrospective analysis of prospectively collected data. This study was approved by the Institutional Review Board at the Wakayama Medical University Hospital (WMUH). The committee that approved the research confirmed that all research was performed in accordance with relevant guidelines/regulations. Written informed consent was obtained from all participants and all research was performed in accordance with the Declaration of Helsinki.
Between May 1, 2017 and March 31, 2021, 486 patients underwent radical gastrectomy for GC at WMUH. Of these, 152 patients underwent RG, 311 patients underwent LG, and the remaining 23 patients underwent open gastrectomy. Patients with GC that underwent RG were included as part of a clinical trial (UMIN000027969/000031536) . Among the 152 patients that underwent RG, we excluded two patients that required conversion to laparoscopic surgery due to machine trouble, and one patient that required conversion to open surgery due to portal vein injury . The remaining 149 consecutive patients were included in this retrospective study.
Tumor stage was classified by the International Union Against Cancer TNM criteria, Eighth Edition . Operation time was defined as the time from the skin incision to skin closure, and console time was the overall surgery time at the console. All surgical and medical complications and mortality events were documented. Postoperative complications were analyzed according to Clavien-Dindo classification . Complications higher than grade II were considered to be clinically significant . Surgical complications were confined to events that occurred within 90 days after surgery; these included anastomotic leakage, pancreatic fistula, intra-abdominal abscess, intra-abdominal bleeding, intraluminal bleeding, ileus, cholecystitis, anastomotic stenosis, and wound infection . Medical complications included pulmonary, cardiovascular, liver, urinary and thrombosis events . Intra-abdominal infectious complications were defined as anastomotic leakage, pancreatic fistula, and intra-abdominal abscess . Reoperation cases were defined as any reoperation connected with any surgery-related complications . Mortality was defined as any death that occurred during the hospital stay .
Details of the RG procedures performed at WMUH have been previously described [9, 12, 13]. All RG procedures were performed using da Vinci S, Si or Xi Surgical System (Intuitive, Sunnyvale, CA, USA) with four articulating robotic arms; a central second arm for a 30° rigid endoscope, a first arm for fenestrated bipolar forceps, a third arm for monopolar scissors, and a fourth arm for Cadiere forceps . One additional port for assisting forceps was placed at the right umbilical level. D1 or D1+ dissection was applied for clinical stage IA tumors, while D2 or D2 plus para-aortic nodal dissection was performed for tumors higher than clinical stage IB . We performed lymph node dissection using monopolar scissors and a Vessel Sealer. Lymph node dissection was completed intracorporeally [9, 12, 13]. Intracorporeal anastomosis was performed using linear staplers, such as gastroduodenostomy, gastrojejunostomy, or esophagojejunostomy [15-18]. All operations were performed or overseen by one senior surgeon (T.O.) as a console surgeon or instructor.
SPSS version 24.0 (SPSS, Chicago, IL) was used for all statistical analyses. Quantitative results are expressed as medians and ranges. To identify risk factors for postoperative intra-abdominal infectious complications, we analyzed univariate and multivariate logistic regression. In the multivariate analysis, risk factors with a univariate P<0.20 were included, and risk factors with a multivariate P<0.05 were defined as independent risk factors.