It was well known that total gastrectomy combined with complete D2 lymphadenectomy and esophagojejunostomy was a technically difficult procedure compared to distal gastrectomy for more lymph node dissection [12]. Nonetheless, we have described our experience with LATG in the treatment of AGC in 2013, which indicated that LATG was a feasible and safe alternative to standard open gastric resection with similar short-term and long-term results [28]. When it comes to RATG, Yoon et al. and Son et al. both reported comparable short-term surgical and oncologic outcomes between RATG and LATG, and yet the EGC patients accounted for a large percentage in their studies[21, 22].. Current studies mostly compared RATG with LATG with the aim to present surgical outcomes of EGC or conducted a stratified analysis when compared the two surgical procedures together with distal gastrectomy. Ye’s study, a total of 205 patients of AGC who under RATG or LATG, reported that RATG had longer operation time, more RLNs, less operative blood loss and volume of abdominal drainage compared to LATG, the complication rate was also comparable (7.5% vs.9.1%, p=0.915)[23].To the best of our acknowledge, our study firstly reported the short-term outcomes of RATG compared with LATG for AGC using the PSM method to reduce bias.
Generally, robotic gastrectomy was known to have some advantages over laparoscopic surgery in reducing perioperative bleeding[16, 23, 29]. In our study, we also concluded that robotic surgery can reduce intraoperative bleeding compared to laparoscopic surgery before PSM (151.98±92.83 vs. 175.53±106.58ml, p=0.007), and after PSM (151.98±92.83 vs. 172.59±97.01ml, p=0.032). Although we have confirmed that RATG can significantly reduce intraoperative bleeding in both cohorts, the mean difference of approximate 20mL blood loss between the two minimal invasive groups may not make much clinical benefit for every individual patient. However, the present study demonstrated that the operative time of RATG was significantly longer than that of LATG before and after PSM, which was consistent with the previous studies[21-23]. The docking time of robot arms, the time for arm change during clipping, and the lack of experience of the assistants may explain the longer operative time[21]. The docking time of robotic surgeries was between 20 and 60 min as reported in a meta-analysis[30]. Since, all of our surgeons had performed RG for more than 30 cases, which means that docking time mainly accounts for the prolonged operating time. Hence, the extra time spent in our study (approximately 20 min) for robotic surgery could be acceptable as docking time was inevitable.
D2 lymphadenectomy is an indispensable process for the application of minimally invasive surgery for AGC[31]. Or rather, the dissection of N2 area is the most crucial part of lymphadenectomy. It has been reported that robotic surgery could retrieve more dissected lymph nodes, especially in the technically demanding N2 area especially in the suprapancreatic area and the splenic vessels[32]. Besides, Son et al. found that robotic spleen-preserving total gastrectomy could retrieve more LNs around splenic vessels and hilum than laparoscopy, and they even compared each group and the metastasis of them[22]. At the same time, subgroup analysis of a meta-analysis revealed that the number of RLNs of RG was significantly higher than that of LG (p=0.03)[30]. Our study also concluded that RATG can retrieve more N2 tier (p=0.001 vs. p=0.018), compared with LATG both before and after PSM. Nevertheless, the difference of RLNs between the two methods was not much clinically significant. Moreover, the study by Shen et al. which included 23 robotic and 75 laparoscopic total gastrectomy reported that RAG and LAG groups had no significant difference in the number of harvested lymph nodes[29]. Li et al. found in their stratified analysis of 92 patients after PSM that the average number of RLNs was not significantly different between robotic and laparoscopic total gastrectomy (30.6 vs. 32.0; p=0.406)[33]. Therefore, it was still controversial whether RATG can retrieve more lymph nodes. According to our experience, the advantage of RG was that the assistant arm could steadily pull the stomach and omentum to the opposite side of abdominal cavity to ensure a roomy operation field which made the dissection of No.2, 10, 11p, 11d more easily than LG. Besides, RG had advantages of articulated movement, elimination of physiologic tremor, a three-dimensional view and a steady image. These merits contributed to precise dissection around the vessels which could result in a large number of RLNs[31]. Taking all those into account, we still hold the view that RATG was capable of retrieving more lymph nodes than LATG because of its advantages. However, further studies of RATG, especially RCTs, should be conducted to confirm our view.
Postoperative complication was an important factor to evaluate the safety and feasibility of a surgical procedure. We evaluated the postoperative complications according the Clavien-Dindo classification system, which was applicable in most parts of the world and among different surgeons, centers, and therapies[24]. Previous studies have proved that the complication rate of laparoscopic total gastrectomy varied from 9.1% to 34.6% [14, 21-23, 33, 34]. In the current study, the complication rate of the RATG group was not significantly different from that of LATG group before PSM (24.1% vs. 28.7%; p=0.341) and after PSM (24.1% vs. 33.6%; p=0.102).The complication of gradeⅠand Ⅲa in LATG group were higher after PSM which made the complication rate up to 33.6% and verged on being significant (p=0.102). Not surprisingly, pulmonary complications obviously accounted for most of the complications in this study. Upper abdominal surgery combined with pneumoperitoneum and postoperative pain would affect the activity of diaphragm and led to micro-atelectasis which causes pulmonary dysfunction in return. More important, TG was an independent risk factor for pulmonary complications[35]. Moreover, anastomosis complications were considered to be one of the most serious complications after TG, which would result in poorer quality of life, prolonged hospital stay, and increased surgery-related costs and mortality[36]. We performed esophagojejunal anastomoses mostly extracorporeally and rarely intracorporeally. The extracorporeal surgical procedures had been described previously [37] and the intracorporeal method used liner stapler or hand-sewn to complete the anastomoses. The Japanese National Clinical Database (NCD) of digestive surgery reported that the incidence of anastomotic leakage after total gastrectomy was 4.4% (881 of 20011) in 2011[38]. Of all the 360 patients included in the analysis, 5 patients in RATG and 10 in LATG encountered anastomosis-related complications (4.3% vs.4.1%; p=0.925, OR=1.054, 95%CI: 0.352-3.157). The anastomosis-related complications in the present study were slightly less than those in the previous studies. Besides, the severe complication (Clavien-Dindo grade ≥IIIa) rate was also comparable between the two cohorts.
Since total gastrectomy was the most common choice for the upper gastric cancer which included tumors in proximal third of the stomach and EGJ cancers [6-8], we conducted another analysis by grouping the patients according to tumor location. RATG for tumor located at EGJ has a tendency to shorter operative time, less intraoperative bleeding and more RLNs compared to the non-EGJ group. However, all those differences may be attributed to that the EGJ group has smaller tumor size which making it easier to perform surgery. As we have already mentioned above that RG can manage the fundus of stomach and esophageal hiatus easier than LG on account of its merits. In spite of not much statistical significance, RATG has an advantage dealing EGJ cancer compared with LATG in our view combining with specific surgical experience.
However, this study has several limitations. First, results were based on a retrospective analysis from a single-clinic institution. Second, the present study lacks a detailed comparative analysis of cost-effectiveness and gastrointestinal function recovery index between robotic and laparoscopic gastric surgery because this is a retrospective study. Third, although the five surgeons who perform the surgeries received robotic surgery certification and were experienced in both the two minimal invasive surgeries, different surgeons can still cause some bias and further influence the results. Despite this study has some limitations, our findings provide evidence for minimal invasive surgery of total gastrectomy for AGC. In addition, further well designed studies, especially RCTs or prospective trials, are needed to assess the impact of RATG and LATG.