Background Gastric adenocarcinoma is an aggressive disease with frequent lymph node (LN) metastases for which lymphadenectomy results in a survival benefit. In the US, the National Comprehensive Cancer Network guidelines recommend D2 lymphadenectomy or a minimum of 15 LNs retrieved. However, retrieval of only 15 LNs is considered by most international guidelines as inadequate. We sought to evaluate the survival benefits associated with a more complete lymphadenectomy. Study Design An international database was constructed by combining gastric cancer cases from the Surveillance, Epidemiology, and End Results program database (n = 13,932) and the Yonsei University Gastric Cancer database (n = 11,358) (total n = 25,289). Kaplan-Meier survival analysis was performed along with Joinpoint analysis to obtain the optimal number of LNs to retrieve based on survival. Prognostic significance of number of nodes retrieved was then confirmed with univariate and multivariate analyses. Results Analysis for both mean and median survival yielded 29 LNs removed as the Joinpoint. This was confirmed with multivariate analysis, where 15 retrieved LNs cutoff fell out of the model and 29 retrieved LNs remained intact, with a hazard ratio of 0.799 (95% CI 0.759 to 0.842; p < 0.001). Stage-stratified Kaplan-Meier analysis for a cutoff point of 29 LNs also demonstrated a statistically significant improvement in survival. Conclusions Joinpoint analysis has allowed for the creation of a model demonstrating the point at which additional dissection would not provide additional benefit. This large international dataset analysis demonstrates that the maximal survival advantage is seen by performing a lymphadenectomy with a minimum of 29 LNs retrieved.
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