The UGIRA International Registry for RAMIG for Gastric Cancer

Gastric cancer is the 3rd most common cause of cancer related deaths worldwide. For resectable gastric cancer, gastrectomy with curative intent combined with an adequate lymphadenectomy results in a 5-year survival rate of 10 - 30%. Survival can be improved by neoadjuvant or perioperative chemotherapy (FLOT-regimen) due to tumor volume reduction resulting in a higher R0-resection rate and due to targeting of (micro)metastases. Although a traditional open approach for gastrectomy is widely performed and provides adequate oncological results, minimally invasive gastrectomy (MIG) is increasingly implemented over the recent years. The aim of MIG is to minimize surgical trauma while achieving non-inferior oncological results and to reduce morbidity in comparison to open gastrectomy (OG).

Meta-analyses have demonstrated decreased postoperative pain, shorter duration of hospitalization, and improved postoperative recovery and quality of life in favour of MIG compared to OG. MIG reduces wound complications and overall complication rate, although no significant difference was found in complication rates for anastomotic leakage or stenosis, ileus, postoperative bleeding, abdominal abscess and postoperative mortality. The number of retrieved lymph nodes, resection radicality and disease free and overall survival are comparable between MIG and OG, although not many studies reported on these outcomes. Even with the operating time for MIG is prolonged by 45 - 49 minutes, intraoperative blood loss is reduced, and the conversion rate is low, these results show that MIG is feasible, safe and oncological comparable to OG. Morbidity and hospital stay are reduced and quality of life increased as well.

Although it has gained in popularity, MIG involves technical challenges such as impaired depth perception, limited range of motion of instruments and an ergonomically suboptimal posture of the surgeon while operating. Robotic assisted surgery can potentially overcome these challenges since it allows for improved dexterity by 3D-visualization for adequate depth perception and by greater range of motion using EndoWrist (Intuitive Surgical, Sunnyvale, CA, USA) with 7° of freedom, 90° articulation and 540° rotation, mimicking articulation of wrist and hand. Furthermore, tremor suppression, 10-fold enlargement and tool handling controlled by the primary surgeon instead of a secondary assisting surgeon contribute to an improved image stability and smooth movements.

These adjustments optimize surgical precision and facilitate anastomotic techniques and suturing. Robot-assisted minimally invasive gastrectomy (RAMIG) is comparable to MIG regarding safety, technical feasibility, intra- and postoperative morbidity and oncological effectiveness. Some studies suggest RAMIG could achieve a more extensive lymphadenectomy and less intraoperative blood loss, although it may prolong operating time and increase costs in comparison to MIG. However, RAMIG is a demanding proficiency for which training is required to acquire adequate robotic skills. While the learning curve for MIG is around 50 - 60 cases, surgeons experienced in MIG may reach proficiency for RAMIG after only 20 - 25 cases. Since complications rates may be higher for surgeons starting with RAMIG, the duration of the learning period should be minimized in order to prevent unnecessary patient harm. However, most studies are retrospective, single-centered, have limited power due to small sample size, and contain heterogeneity in anastomotic techniques and the extent of lymph node dissection. An unknown learning curve may worry surgeons and could restrain them from implementing RAMIG in their hospitals. Therefore, additional research is warranted to investigate this learning period in detail.

Variation in definitions of complications after gastrectomy lead to differences in reported outcomes, which represents a major challenge when comparing results from multiple centers. Uniform definitions should be used in order to adequately compare complications and their impact on outcomes internationally, which could aid in identifying factors in clinical care which could be improved. Currently, there is no widespread consensus on standardized definitions of complications after gastrectomy. Therefore, the Gastrectomy Complications Consensus Group (GCCG) was formed. Standardize definitions have yet to be published. However, an international registry using an online electronic case report form (eCRF) to uniformly collect perioperative outcomes is essential to minimize such variability. Therefore, this study aims to establish such an international RAMIG registry.

The current initiative aims to expand the collaboration of international experts that was previously established with UGIRA by creating a registry for RAMIG that can be used to initiate international studies and to monitor the surgical quality for surgeons implementing RAMIG in new centers. The UGIRA aims to facilitate the effective implementation and furtherance of robotic esophagogastric surgery. In this context, UGIRA already initiated an international registry for RAMIE and defined a structured training pathway that can be used to guide surgeons starting with RAMIE through their implementation phase. With a more intensified collaboration that also focuses on RAMIG, UGIRA aims to facilitate its worldwide implementation and advancement, and to provide an international platform for discussion and to share surgical vision on topics in this area. This existing experience and UGIRA-network can be used to achieve the key initial aims of the RAMIG registry, which are to create an international registry to gain insight in surgical techniques and postoperative outcomes of RAMIG worldwide, and to evaluate the learning curve for RAMIG.

The principal investigators have previously established an international registry for robot-assisted minimally invasive esophagectomy (RAMIE) supported by Intuitive Surgical Inc. In the context of aiming for worldwide collaboration between international experts in robotic esophagogastric surgery, the UMC Utrecht has co-founded the Upper Gastrointestinal International Robotic Association (UGIRA, www.ugira.org), currently chaired by Richard van Hillegersberg. The UGIRA now includes members from Europe, Asia, North- America and South America (Annex 1), and aims to facilitate the effective implementation and furtherance of robotic esophagogastric surgery.

In the UMC Utrecht, the investigators have developed a structured training pathway that can be used to guide surgeons starting with RAMIE through their implementation phase. It is found that applying this structured training pathway can reduce the learning curve for RAMIE substantially from 70 to 24 cases. Furthermore, no differences were observed regarding postoperative morbidity, mortality and oncological outcomes during the learning phase compared to after completing the learning phase.

Based on these studies, it can be concluded that the structured training pathway is a safe and effective strategy to implement RAMIE in new centers. UGIRA is currently working on establishing a structured training pathway for RAMIG, as was previously done for RAMIE.

Data for this registry is collected prospectively and retrospectively.