The influence of stage migration on the comparison of surgical outcomes between D2 gastrectomy and D3 gastrectomy (para-aortic lymph node dissection): a multi-institutional retrospective study

Background The aim of this study was to determine the influence of stage migration on the outcomes of D2 gastrectomy compared with D3 gastrectomy in advanced gastric cancer. Methods A series of 580 advanced gastric cancer patients (430 D2 gastrectomy and 150 D3 gastrectomy) were registered. The incidence of stage migration and the surgical results of D2 and D3 gastrectomy were compared. Results The incidence of N-stage migration was 22.7% and that of pathological stage was 20.7%. Stage-specific survival times of simulated D2 gastrectomy and real D2 gastrectomy were equal. In patients with pN2 tumors measuring 50 to 100 mm in diameter, there was a significant difference in survival between D2 and D3 gastrectomy. However, no difference was observed between D2 and simulated D2 gastrectomy. Conclusions Because there was a high incidence of stage migration in patients after D3 gastrectomy, it may be more feasible to validate comparisons between different levels of lymph node dissection in a randomized controlled trial.