Impact of anatomical location of positive lymph node on TNM classification in patients with node positive gastric cancer.

Abstract

155 Background: In the 7th edition of TNM classification, node positive gastric cancer is subclassified into three categories (N1, 1-2 positive nodes; N2, 3-6 positive nodes; N3, 7 or more positive nodes) according to the number of positive lymph node (LN). However, anatomical location of positive LN is not taken into account in the TNM classification, although Japanese classification for gastric cancer had adopted anatomical location oriented nodal staging system and had shown relevance between location of positive LN and survival outcome. The aim of the present study is, therefore, to clarify the impact of anatomical location of positive LN on numerical number oriented, latest TNM nodal staging system. Methods: The present study included 1047 node positive gastric cancer patients who underwent curative gastrectomy at the Shizuoka Cancer Center between September 2002 and December 2014. Survival outcomes were compared between patients with positive extra-perigastric lymph node (PEPLN) and those with positive perigastric lymph node (PPLN) in each nodal stage according to the 7th edition of TNM classification. Results: The present study included 471 N1 patients, 309 N2 patients, and 267 N3 according to the 7th edition of TNM classification, and 5-year survival rates (5ysr) were 81.8%, 70.5%, and 51.9%, respectively. In the N1 group, 5ysr was 75.4% in patients with PEPLN, while it was 83.2% in those with PPLN, and the difference was not statistically significant (P = 0.105). It was also similar between patients with PEPLN (64.2%) and those with PPLN (73.8%, P = 0.343) in the N2 group. However, in the N3 group, survival outcome was significantly worse in patients with PEPLN (47.9%) than in those with PPLN (63.9%, P = 0.036). Conclusions: In the N1 and N2 group, involvement of extraperigastric LN did not have impact on survival outcome. On the contrary, in the N3 group, patients with PEPLN showed worse survival outcome than those with PPLN, and they could be potential candidates for intense postoperative adjuvant treatment.