Clinical implication of an insufficient number of examined lymph nodes after curative resection for gastric cancer

Abstract

Background: The 7th edition of TNM staging system increased the required number of examined lymph nodes (LNs) in gastric cancer from 15 to 16. However, the same staging system defines node negative gastric cancer regardless of the number of examined LNs. In this study, we evaluated whether gastric cancer can be properly staged with fewer than fifteen examined LNs. Methods: We analyzed the survival rates of 10,010 patients who underwent curative gastrectomy from 1987 to 2007. They were divided into two groups according to the number of examined LNs, termed the “insufficient” group (≤15 examined LNs) and “sufficient” group (≥16 examined LNs). The survival curves of patients from both groups were compared according to the 7th edition of the TNM classification.Results: Three hundred sixteen patients (3.2%) had fewer than 15 examined LNs for staging after standard curative lymphadenectomy. Patients who had T1, N0 classification, and Stage I disease with an insufficient number of examined LNs after curative gastrectomy showed significantly worse prognoses than those of patients with ≥16 examined LNs. Moreover, an insufficient number of examined LNs was an independent prognostic factor for patients who had T1, N0 classification, and stage I disease.Conclusion: Node negative cancers in which fewer than 15 LNs were examined, classified as N0 in the new TNM staging system cannot adequately predict patient survival after curative gastrectomy, especially in early gastric cancer.