Necessity of harvesting at least 25 lymph nodes in patients with stage N2-N3 resectable gastric cancer: a 10-year, single-institution cohort study.

A minimum of 15 lymph nodes (LNs) has been recommended as an adequate number for radical gastrectomy for gastric cancer (GC). This study aimed to investigate whether the harvesting of at least 25 LNs was a better criterion for stage N2-3 GC based on the 10-year experience of a high-volume hospital. A total of 1363 patients who underwent radical gastrectomy for gastric cancer between 2000 and 2010 were included in this study. The relationship between the number of lymph nodes examined during gastrectomy and overall survival (OS) was analyzed. In multivariate analysis, the numbers of LNs examined (P = 0.001) and N stage were confirmed as 2 of the independent prognostic factors. A larger proportion of N2/N3a/N3b patients was observed in the group with ≥20 LNs examined. The cutoff of ≥25 LNs examined exhibited a significantly lower hazard ratio (HR) than other LN cutoffs among N2-N3 diseases, but the cutoff was not significantly superior to other cutoffs in patients with N0 and N1 disease (HR, 0.64, 0.62, and 0.53 for N2, N3a, and N3b, respectively). The 5-year OS rates were 58.59% and 32.77% for N2 and N3 diseases, respectively, with ≥25 LNs examined, which represents a significant improvement over 15-24 LNs examined (52.48% and 21.67% for N2 and N3 stages, respectively). Among patients with stage N2-N3 GC, harvesting at least 25 LNs may represent a superior cutoff for radical gastrectomy and could yield better survival outcomes.