Influence of lymph node micrometastasis on the staging system for gastric cancer

Objective The aim of this study was to investigate the effect of lymph node micrometastasis on the prognosis of patients with gastric cancer and the necessity of integrating it into the gastric cancer staging system.Methods In total,241 patients with gastric cancer were included.Hematoxylin and eosin staining of lymph nodes was performed,and negative lymph nodes were evaluated by immunohistochemistry to detect micrometastases.Differences in survival rates between stages were evaluated.Results(1)A total of 78 patients(32.4%)had lymph node micrometastases.Compared with the group without micrometastases,the overall recurrence rate,lymph infiltration,vascular invasion,and nerve invasion rate in the micrometastasis group were significantly higher(P<0.05).(2)According to the standard N staging system,the rates of disease-free survival(DFS)for the N0,N1,N2,N3a,and N3b groups were 96.0%,84.0%,67.6%,59.0%,and 21.7%,respectively.There was no significant difference in survival between N2 and N3a.The cumulative survival curves for N2 and N3a intersected.(3)The N stage of 38 patients(15.8%)differed between the traditional system and the new N staging system reflecting micrometastasis.The DFS for N0,N1,N2,N3a,and N3b were 97.0%,86.3%,74.2%,65.4%,and 29.2%,respectively.There was no significant difference in survival between N2 and N3a,but the cumulative survival curves for N2 and N3a did not intersect.(4)Based on a Cox multivariate analysis,various independent risk factors for recurrence were identified(P<0.05).Conclusion Lymph node micrometastasis is an important risk factor for gastric cancer recurrence.Lymph node micrometastasis should be considered in TNM staging to determine prognosis and optimal treatment strategies.