Validation of clinical significance of examined lymph node count for accurate prognostic evaluation of gastric cancer for the eighth edition of the American Joint Committee on Cancer(AJCC) TNM staging system

Objective: To validate the necessity of increasing the examined lymph node(ELN) count for enhancing the accuracy of prognostic evaluation of gastric cancer(GC) patients after curative gastrectomy in multiple medical centers of China.Methods: The clinicopathological data of 7,620 patients who underwent the curative resection for GC between2001 and 2011 were included to demonstrate whether the ELN count is indispensable for enhancing the accuracy of prognostic evaluation of GC patients after surgery. After a meticulous stratification by using the cut-point survival analysis, all included 7,620 patients were allocated into three groups as: less than 16(<16), between 16 and30(16-30), and more than 30(>30) ELNs. Survival differences among various subgroups of GC patients were analyzed to assess the impact of the ELN count on the stage migration in accordance with the overall survival(OS)of GC patients.Results: Survival analyses revealed that the ELN count was positively correlated with the OS(P=0.001) and was an independent prognostic predictor(P<0.01) of 7,620 GC patients. Stratum analysis showed that the accuracy of prognostic evaluation could be enhanced when the ELN count was no less than 16(≥16) for node-negative patients and >30 for node-positive patients. Stage migrations were mainly detected in the various subgroups of patients with specific pN stages as follows: pN0 with 16-30 ELNs(pN0) and pN0 with >30 ELNs(pN0), pN0 with <16 ELNs(pN0) and pN1, pN1and pN2, pN1and pN2, pN3aand pN3b, and pN3aand pN3b. These findings indicate that increasing the ELN count is a prerequisite to guarantee precisely prognostic evaluation of GC patients.Conclusions: The ELN count should be proposed to be >30 for acquiring the accurate prognostic evaluation for GC patients, especially for node-positive patients.