The definition of “R1” lymph node dissection status in patients undergoing curative-aim gastrectomy for gastric carcinoma: A proof of concept study

Introduction: The aim of this study was to define and investigate the prognostic impact of "R1-Lymph-node dissection" during gastrectomy.Methods: This was a retrospective study conducted with 499 patients undergoing curative-aim gastrectomy. We defined R1-Lymph dissection as an involvement of lymph node stations anatomically connected with lymph node stations outside the declared level of dissection (D1 to D2+). The primary outcomes were disease-free and disease-specific survival (DFS and DSS).Results: At multivariable analysis, the type of gastrectomy, pT and pN were associated with DFS, and the type of gastrectomy, R1-Margin status, R1-Lymph status, pT, pN and adjuvant therapy were associated with DSS. Moreover, pT and R1-Lymph status were the only factors associated with overall loco-regional recurrence. Conclusions: In this study, we introduced the concept of R1-Lymph-node dissection, which was significantly associated with DSS and appeared to be a stronger prognostic factor for loco-regional recurrence than the R1 status on the resection margin.