Prognostic value of a new staging system based on the retrieved number and metastatic rate of LNs in gastric cancer with ≤15 retrieved LNs

Abstract

ObjectiveTo investigate a reasonable lymph node (N) staging system for gastric cancer patients with ≤15 retrieved lymph nodes (LNs). MethodsThe clinicopathological and follow-up data of patients with ≤15 LNs were obtained from the US Surveillance, Epidemiology, and End Results (SEER) database to analyze the impact of the number of retrieved LNs and metastatic status on the prognosis. In addition, external validation was achieved with data from two medical centers in China. ResultsA total of 18,139 gastric cancer patients with 1–15 retrieved LNs from the SEER database were enrolled and randomly divided into the training group and the internal validation group. A new LN staging system, mNr staging (mNr0-4; 5 stages), was established according to the number of retrieved LNs and the metastatic rate. Compared with the TNM and TNrM staging systems (established by Wang J; misclassification rates of 50.4% and 62.5%, respectively), the mTNrM staging system had a lower misclassification rate (23.4%). Furthermore, there was a significant difference in the 5-year overall survival (OS) rate between the mTNrM staging subgroups (p < 0.05); however, no significant difference was found in the 5-year OS rate of partial adjacent stages in the TNM (8th edition) and TNrM (p > 0.05) staging systems. Similar results were obtained in the external validation cohort.Conclusion: mNr and mTNrM staging systems can efficiently distinguish a survival difference in patients who undergo gastrectomy with ≤15 retrieved LNs, with more accurate predictions of the 5-year OS rate of patients compared with the TNM and TNrM staging systems.