Number of retrieved lymph nodes is an independent prognostic factor after total gastrectomy for patients with stage III gastric cancer: propensity score matching analysis of a multi-institution dataset

Abstract

Background: The prognostic significance of the number of retrieved lymph nodes (RLNs) in gastric cancer remains controversial. Therefore, we designed a multicenter collaborative database to investigate the correlation between the number of RLNs and prognosis of patients with advanced gastric cancer after curative resection. Methods: We retrospectively analyzed 1103 patients who underwent gastrectomy for stage II/III gastric cancer between 2010 and 2014. Lymph nodes, which were retrieved by surgeons from surgically resected specimens, were validated by pathologists. A target population and the optimal cutoff were determined using receiver operating characteristic (ROC) curve analysis. After propensity score matching of eight variables, including splenectomy and adjuvant chemotherapy, the prognostic significance of RLNs was evaluated. Results: According to ROC curve analysis, the optimum cutoff score for predicting postoperative survival was 40. After matching, the backgrounds of patients in the RLN < 40 and RLN ≥ 40 groups (n = 87 each) became well-balanced. The RLN < 40 group experienced significantly shorter relapse-free and overall survival. The prevalence of peritoneal recurrence was significantly increased in the RLN < 40 group. RLN < 40 was an independent prognostic factor in multivariable analysis, although pathological N status was not. A forest plot revealed that the RLN < 40 group was at greater risk of recurrence in most subgroups. Conclusions: RLN < 40 was associated with an adverse prognosis of patients with stage III gastric cancer who underwent total gastrectomy.