Abstract
BackgroundThe eighth TNM classification for gastric cancer categorizes N3 as N3a and N3b in the final pathologic stage. The cutoff for N3a/N3b is defined as 15 metastatic lymph nodes, but the rationale for this cutoff remains unclear. This study aimed to determine the optimal N3a/N3b cutoff and evaluate its prognostic significance.MethodsAn international database was constructed by combining data from patients with N3 gastric cancer and complete five-year follow-up data from the Surveillance, Epidemiology, and End Results program database (n = 1833) and the Fujian Medical University Union Hospital database (n = 920) (total n = 2753). A log-rank test was performed to determine the optimal N3a/N3b cutoff, and its prognostic significance was confirmed in a two-step multivariate analysis and compared to that of the eighth TNM.ResultsA cut-point analysis performed at each metastatic lymph node number identified the greatest survival difference between N3a and N3b at 13 metastatic lymph nodes (χ2 = 157.671, P = 3.65 × 10− 36). In patients with 14–15 metastatic lymph nodes, prognoses were significantly worse than those in patients with 7–13 metastatic lymph nodes (P < 0.001) but similar to those in patients with > 15 metastatic lymph nodes (P = 0.078). Therefore, patients with 14–15 metastatic lymph nodes were incorporated into a modified N3b classification. In the two-step multivariate analysis, the eighth N3 classification fell out of the model, while the modified N3 classification remained intact (HR 1.51, P < 0.001). Further analyses demonstrated that the modified TNM classification had superior homogeneity, discriminatory ability, and gradient monotonicity compared to the eighth TNM classification.ConclusionsFor improved prognostic stratification, we recommend adjusting the cutoff for subclassification of N3 gastric cancer to 13 metastatic lymph nodes.
Highlights
The eighth TNM classification for gastric cancer categorizes modified tumornode-metastasis stage (N3) as N3a and N3b in the final pathologic stage
There was no significant difference in pT-stage-T2, N3 stage, pIIIa and pIIIb stage tumors or in the median number of metastatic lymph node (MLN)
Cut-off point survival analysis of N3a/N3b gastric cancer As shown in Fig. 1, we examined the ability of each cutoff value to detect survival differences and found that a cutoff value of 13 MLNs most significantly stratified the prognoses of N3 patients into N3a and N3b groups (7–13 MLNs vs > 13 MLNs, five-year survival rate: 31% vs 15%; χ2 = 157.671, P = 3.65 × 10− 36) (Table 2)
Summary
The eighth TNM classification for gastric cancer categorizes N3 as N3a and N3b in the final pathologic stage. Two major classification systems are used for gastric cancer staging. These include the Japanese Classification of Gastric Cancer (JCGC) and the Union for International Cancer Control/American Joint Committee on Cancer (UICC/AJCC) TNM classification system. Lin et al BMC Cancer (2019) 19:21 definitions of the N3 subclasses (N3a and N3b) were not different with regard for the final pathological stage [4, 5]. The seventh UICC/AJCC classification for LN metastases has been described as reliable for predicting prognoses in gastric cancer in many studies. The eighth TNM classification detailed N3 as N3a and N3b in the final pathological stage of the disease [9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
