Do all the European surgeons perform the same D2? The need of D2 audit in Europe.

Although D2 lymphadenectomy is the standard of care for radical intent surgical treatment of gastric cancer, the real compliance with D2 dissection in Europe is still unknown. The aim of the present study is to analyze the variation in lymph-node harvesting reported after D2 dissection in European series and to present a European project aiming at evaluating the real compliance with D2 lymphadenectomy. A PubMed search for papers using the key words "D2 lymphadenectomy" and "gastric cancer" from 2008 to 2017 was undertaken. Only studies by European authors in English language reporting the number of retrieved lymph nodes after D2 lymphadenectomy were included. The results of literature review were descriptively reported. The literature survey yielded 16 studies: 2 RCTs, 3 observational multicentre studies, and 11 observational monocentric studies. A large variability was found in the number of retrieved nodes, which, overall, was the lowest in the surgical series from Eastern Europe (16.6 and 19.9 in the Lithuanian and Hungarian series, respectively) and the highest in an Italian RCT. The within-study variability was also quite high, especially in multicentre RCTs and observational studies. Sample size tended to have a larger effect on the variability of lymph nodes retrieved than on its actual value. However, in both cases, the relation was not significant, due to the low number of studies considered. There is a large variability in the number of retrieved nodes after D2 dissection in European series. This reflects, at least partly, different approaches to D2 lymphadenectomy by European surgeons and may be responsible of the different outcomes observed in patients with gastric cancer across Europe. Therefore, there is the need to standardize the practice of D2 gastrectomy in Europe and to define possible variations of D2 procedures according to tumour's characteristics.