Prognostic significance of the number of negative lymph nodes in postoperative locally advanced gastric cancer patients

Abstract

OBJECTIVE To evaluate the impact of the number of negative lymph nodes on disease free survival (DFS) in patients with locally advanced gastric cancer. METHODS A total of 485 patients who underwent surger for locally advanced gastric cancer (pT3N0-2M0) and had a DFS at least 6 months were enrolled in this retrospective study. The medical records of the patients were reviewed in detail, and the characteristics of the patients and the findings of pathologic examination were analyzed in order to find the potential association with DFS. Subgroup analysis according to pathologic stage was performed. Multivariate analysis using the COX regression method was also conducted in order to identify the independent prognostic factors. The Kaplan-Meier method was used to plot DFS curves. The DFS rate was compared in each subgroup. RESULTS COX regression analysis showed that the DFS rate of gastric cancer patients with pathologic stage T3N0-2M0 was significantly associated with age, degree of tumor differentiation, tumor location as well as the number of negative lymph nodes. Among patients with stage T3N0M0 disease, who had 1-4 and 5 or more negative lymph nodes, the 2-year DFS rate was 8.3% and 55.6%, respectively. Meanwhile, the 3-year DFS rates of the same group of patients was 0% and 24.9%, respectively ( P = 0.025). In the T3N1M0 subgroup, the 2-year DFS rate of patients with 3 or fewer, 4-9, and 10 or more negative lymph nodes was 17.3%, 39.1%, 52.6%, respectively. The 3-year DFS rate in this group was 4.2%, 6.0%, 17.1%, respectively ( P < 0.001). In the T3N2M0 subgroup, the 2-year DFS rate of patients with 7 or fewer and 8 or more negative lymph nodes was 11.5% and 35%, respectively. The 3-year DFS rate of the same group of patients with 8 or more negative lymph nodes was also significantly improved (0.8% vs. 5%, respectively; P = 0.015). CONCLUSION For gastric cancer patients with pathologic stage T3N0-2M0, the number of negative lymph nodes is an independent prognostic factor for DFS. The number of negative lymph nodes may reflect the level of regional lymph node dissection or the accuracy of the pathologic staging.