This single-center retrospective analysis of prospectively collected data was approved by the Institutional Review Board (IRB) at the Wakayama Medical University Hospital (WMUH). All patients underwent RG and gave written informed consent in accordance with the IRB guidelines.
Between May 1, 2017, and January 31, 2021, 476 patients received radical gastrectomy for GC at WMUH. Of these, 150 underwent RG and the 303 patients received LG and the remaining 23 open gastrectomy. Patients with GC that underwent RG were included as part of a clinical trial (UMIN000027969/000031536). Among patients that underwent RG, we excluded one patient with GC in the remnant stomach after gastrectomy and one patient with cancer at the esophagogastric junction that required intrathoracic anastomosis. The remaining 148 consecutive patients were included in this retrospective study.
We began using RG in 2017 with the da Vinci S Surgical System. In January 2018, it was replaced by the Si and Xi systems and we subsequently performed RG procedures exclusively with the new systems. We used da Vinci Xi on Mondays and Si on Wednesdays. This study compares the short-term surgical outcomes of the RG using the da Vinci S, Si and Xi systems.
Tumor stage was classified by the International Union Against Cancer TNM criteria, Eighth Edition14. All surgical and medical complications and mortality events were documented. Postoperative complications were analyzed according to Clavien-Dindo classification15. 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. Reoperation cases (= grade IIIb) were defined as any reoperation connected with any surgery-related complications. Mortality was defined as any death that occurred during the hospital stay.
Operation time was defined as the time from the skin incision to skin closure, docking time was the time from the trocar placement to being ready to start the console, and console time was the overall surgery time at the console.
Details of the RG procedures performed at WMUH have been previously described1,2. All RG procedures were performed using da Vinci S, Si or Xi Surgical System with four articulating robotic arms; a central arm for a 30° rigid endoscope, a first arm for monopolar scissors, a second arm for fenestrated bipolar forceps, and a third arm for Cadiere forceps. One additional port for assisting forceps was placed at the right umbilical level. Robotic ultrasonically activated device (USAD) does not have wrist-like motion, and does not, therefore, have robotic articulated function. For these reasons, we did not use robotic USAD. D1 or D1+ dissection was applied for clinical stage IA tumors, while D2 or D2 + para-aortic nodal dissection was performed for tumors higher than clinical stage IB16. Dissection of lymph node station 14v was optional, but an omentectomy was essential for tumors higher than clinical T216. The greater omentum was resected up to the inferior portion of the spleen. The left gastroepiploic vessels were dissected at the point before the first branch (nos. 4d, 4sb). After completion of omentectomy, the root of the right gastroepiploic vein and artery were isolated and transected (no. 6). The root of the right gastric artery was isolated in the hepatoduodenal ligament and transected (no. 5). The lesser omentum along the liver edge to the esophagogastric junction was resected. The peri-gastric lymph nodes were dissected along the upper lesser curvature up to the esophagogastric junction (nos. 1 and 3). For robotic D1+ lymphadenectomy, the lymph nodes around the celiac trunk (no. 9) were dissected, and the root of the left gastric vein and artery were isolated and transected (no. 7), and successively, the lymph nodes along the common hepatic artery were dissected (no. 8a). For robotic D2 lymph node dissection, the lymph nodes along the proper hepatic artery (no. 12a) and along the splenic artery (no. 11) were also dissected. Lymph node dissection was completed intra-corporeally. In RG using articulating forceps, lymphadenectomy without touching the pancreas was possible. Intracorporeal anastomosis using linear staplers, such as gastroduodenostomy, gastrojejunostomy, or esophagojejunostomy was performed17-19. When an incision exceeding 10 cm was required for the control of intraoperative complications or tumor extension, the procedure was defined as a conversion to open surgery.
SPSS version 24.0 (SPSS, Chicago, IL) was used for all statistical analyses. Quantitative results are expressed as medians and ranges. Statistical comparisons between three groups were performed using chi-squared statistics, in the case of two groups it was by Mann-Whitney U test. A P < 0.05 was considered to be significant.