Prognostic Significance of the Number of Metastatic Lymph Nodes: Is UICC/TNM Node Classification Perfectly Suitable for Early Gastric Cancer?

Abstract

Metastatic lymph node (MLN) is less frequently involved in early gastric cancer (EGC) and barely exceeds six in number. The prognostic value of the 5th edition of the UICC tumor–node–metastasis (TNM) node classification appears to be less accurate when applied to patients with EGC and needs to be further stratified. Three hundred twenty-three EGC patients were enrolled into this study. Prognoses of these patients were first assessed based on the 5th edition UICC TNM classification, followed by a reevaluation in which the prognoses of patients were further stratified according to the number of MLNs involved with an increment of one node at a time. A new node classification was proposed based on the correlation between prognoses and the number of positive nodes. According to the prognostic value, a new node classification was categorized as new N0 (0 MLN), new N1 (1–3 MLNs), new N2 (4–6 MLNs), and new N3 (>6 MLNs). While the survival of N0 and N1 groups based on the 5th edition UICC TNM classification appeared to be homogeneous (p = 0.0947), significant difference was unmasked between the new N2 and new N0/N1 groups (p < 0.001). In addition, differentiation status, vessel involvement, and new node classification were identified as independent prognostic factors by multivariate analysis for EGC. We conclude that subsets exist in patients with EGC at stage IB by UICC classification; patients with ≥4 MLNs are at higher risk of recurrence and surgical outcome in this population is relatively poor.