D1-plus vs D2 nodal dissection in gastric cancer. A propensity score matched comparison and review of published literature

Background: The results of D1-plus lymphadenectomy following gastric resection are seldom investigated. The aim of this study was to compare results of D1-plus vs D2 resections and to provide a literature review. Methods: Patients who underwent upfront R0 gastrectomy for adenocarcinoma from 2000 to 2016 in three Institutions were selected using propensity scores and categorized according to lymphadenectomy. Statistical analyses were performed for the nodal harvest (LNH) and survival. Published literature comparing D1-plus and D2 was reviewed and analyzed according to PICO and PRISMA guidelines. Results: Two matched groups of 93 D1-plus and 93 D2 resections were selected. LNH was significantly greater in D2 vs D1-plus dissections (mean 31.2 vs 27.2, p 0.04), however LNH distribution was similar. The cumulative incidence curves for overall survival, disease free and disease specific events did not report significant differences, however Cox regression analysis disclosed that total gastrectomies (HR 1.8; 95% 1.0-2.9), advanced stages (HR 5.9; 95% 3.4-10.3) and D1-plus nodal dissection (HR 2.1; 95% 1.26-3.50) independently correlated with disease free survival. Literature review including 297 D1-plus and 556 D2 lymphadenectomies documented LNH in favor of D2 sub-group (SMD -0.772; 95%CI -1.222- -0.322). Conclusion: D2 provided greater LNH than D1-plus dissections; prospective studies should aim to investigate long-term survival of D1-plus lymphadenectomy.