Development and validation of a novel staging system integrating the number and location of lymph nodes for gastric adenocarcinoma

Ziyu Li,Fei Shan,Jiafu Ji,Xiaolong Wu,Xiangji Ying,Yan Zhang,Xiangyu Gao

doi:10.1038/s41416-020-01190-z

Ziyu Li, Fei Shan + Show 5 more

Open Access

https://doi.org/10.1038/s41416-020-01190-z

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Abstract

BackgroundEvidence suggests that the anatomic extent of metastatic lymph nodes (MLNs) affects prognosis, as proposed by alternative staging systems. The aim of this study was to establish a new staging system based on the number of perigastric (PMLN) and extra-perigastric (EMLN) MLNs.MethodsData from a Chinese cohort of 1090 patients who had undergone curative gastrectomy with D2 or D2 plus lymphadenectomy for gastric cancer were retrospectively analysed. A Japanese validation cohort (n = 826) was included. Based on the Cox proportional hazards model, the regression coefficients of PMLN and EMLN were used to calculate modified MLN (MMLN). Prognostic performance of the staging systems was evaluated.ResultsPMLN and EMLN were independent prognostic factors in multivariate analysis (coefficients: 0.044, 0.115; all P < 0.001). MMLN was calculated as follows: MMLN = PMLN + 2.6 × EMLN. The MMLN staging system showed superior prognostic performance (C-index: 0.751 in the Chinese cohort; 0.748 in the Japanese cohort) compared with the five published LN staging systems when MMLN numbers were grouped as follows: MMLN0 (0), MMLN1 (1–4), MMLN2 (5–8), MMLN3 (9–20), and MMLN4 (>20).DiscussionThe MMLN staging system is suitable for assessing overall survival among patients undergoing curative gastrectomy with D2 or D2 plus lymphadenectomy.

Highlights

Evidence suggests that the anatomic extent of metastatic lymph nodes (MLNs) affects prognosis, as proposed by alternative staging systems
According to the Japanese Gastric Cancer Association (JGCA) guidelines,[28] D2 lymphadenectomy cannot be performed during proximal gastrectomy; patients treated with proximal gastrectomy were excluded
A modified numeric-based LN staging system, namely, the modified MLN (MMLN) staging system was established by combining the prognostic weights of perigastric MLN (PMLN) and extraperigastric MLN (EMLN)

Summary

Introduction

Evidence suggests that the anatomic extent of metastatic lymph nodes (MLNs) affects prognosis, as proposed by alternative staging systems. Comprehensive and appropriate therapeutics, including endoscopy, surgery, radiotherapy, chemotherapy, and immunotherapy, have improved outcomes of gastric cancer patients.[1,2,3,4,5] Surgery remains vital in the treatment of resectable, non-metastatic gastric cancer.[6] Tumour invasion depth and lymph node (LN) status— used in almost all gastric cancer staging systems—are essential independent prognostic factors for overall survival (OS), following a microscopically margin-negative (R0) resection.[7,8,9,10]. Other authors have proposed LN ratio (LNR), the ratio of metastatic LNs relative to the total number of retrieved LNs, and log odds of metastatic LNs (LODDS), defined as the log of the ratio between the probability of being a positive LN and the probability of being a negative LN, which might be better LN staging systems, as they take into account the number of LNs retrieved during surgery.[20,21,22,23]

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