Extension of lymphadenectomy for gastric cancer:Audit at European specialist centres.

Gastric cancer is still one of the leading causes of cancer-related deaths worldwide, and its treatment management differs between Eastern Asia and Western countries. Screening program, early diagnosis, and surgical treatment was primarily established in Japan and was rapidly disseminated to other countries. In other parts of the world, such as the USA and Western Europe, the incidence of gastric cancer has declined, and efforts for screening and early detection have not been an issue of higher priority over the management of other diseases. Thus, gastric cancer in the West is often more advanced and is either inoperable or needs more radical surgery for resection. The only treatment method that can potentially cure gastric cancer is the surgical approach. Depending on the extension of the tumor, surgeons may execute an operation that involves removing all or part of the stomach with some nearby lymph nodes (lymphadenectomy). Lymphadenectomy is a crucial step during surgical operation that involves the removal of one or more lymph nodes located in the drainage area of a tumor, in which there is a high possibility of lymph node metastasis. The Japanese guidelines define the criteria of lymphadenectomy procedure into D1 D1+ or D2 according to the type of gastrectomy executed. The extent of lymphadenectomy has long been a subject of debate. Indeed, Japanese surgeons introduced extended lymphadenectomy (D2), which has also been progressively adopted in Europe and included in almost all international guidelines. However, the procedure requires a long learning curve, which involves a high volume of interventions; therefore, US guidelines do not recommend the D2, and many Italian and European centres do not yet perform this procedure. Indeed, the current European Consensus guidelines recommend D2 dissection in regional specialist centres for patients with moderate comorbidity. However, compliance with guidelines is unclear, and in some recent RCTs, the standard approach of surgical treatment is at the "surgeon's discretion." This study aims to evaluate the current practice of D2 lymphadenectomy in Europe to determine any variation in practice and compare it with the Japanese guidelines. The study consists of two parts: first, a questionnaire based on hypothetical clinical scenarios was administered to expert surgeons belonging to European Chapter of the International Gastric Cancer Association from high-volume European centers. They were asked to select the appropriate lymphadenectomy extension for each hypothetical case and the associated lymph node stations to remove. In the second part of the study, the same surgeons were asked to collect their data about gastric cancer gastrectomies performed in 2015 for comparative analysis. The study results show that the expert surgeons of high-volume centres are quite in agreement with the choice of D2 lymphadenectomy in the different clinical scenarios. The surgical choice seems to have been influenced by the tumor stage, site, and histology of the tumor. More specifically, the D2 procedure is recommended for cases with diffuse histology compared to tumors with intestinal histology. However, the selection of the D2 dissection procedure rarely conformed to Japanese guidelines: the choice of lymph node stations revealed the presence of a wide variation in execution. In the review of the gastrectomy experience, it was observed that a high surgical standard was achieved: in fact, in 97% of gastric cancer gastrectomies after D2, an adequate number of lymph nodes (≥15 nodes) were removed. In conclusion, even if an adequate lymphadenectomy was obtained in almost all cases in dedicated centers, there is still significant variability in the number of recovered lymph nodes. The histology of the tumor largely influences the surgeon's choice regarding the extent of the lymphadenectomy; however, the role of histology in the planning of surgical procedures is not considered in the current guidelines and must be verified in prospective studies.