Lymph node metastasis in gastric cancer: Location of positive station to predict survival after preoperative therapy.

Abstract

166 Background: We sought to determine the association between the identification of positive lymph nodes on D2 lymph node dissection (LND) with stage and outcomes, in the era of preoperative treatment for gastric cancer. Methods: We reviewed data from a prospectively maintained database of gastric cancer patients who underwent resection of gastric or gastroesophageal cancer at our institution from 2005-2016. Central lymph nodes (CnLN) were defined as common hepatic, celiac, and proximal splenic artery lymph nodes (stations #8, 9, and 11p). Risk factors for CnLN metastases, and overall survival (OS) were examined. Results: We identified 356 patients, median age was 64 years (IQR 54-71) and 59% were male. Preoperative therapy was given in 66% of patients. D2 LND was performed in 80% of patients, and the median number of LN examined was 25 (IQR 18-34). Most patients (N = 244, 68%) had separately-examined CnLN in pathology and the median number of examined LNs was higher in this group (27 vs 19; p < 0.001). The CnLN positivity rate was 9.1% (22/244; #8: 4.8%, #9: 6.1%, and #11p: 4.8%), which was higher in advanced pT stage patients (pT0 - 3%, pT1 - 0%, pT2 - 6%, pT3 - 18%, pT4 - 13%; p = 0.001). If we assume that D2 LND was not performed on these patients, a total of 7 (3%, 7/244) patients would have had pN stage down-migration (6 with N1 to N0, 1 with N2 to N1). Of the 22 CnLN-positive patients, 10 (45%) had pN1, 2 (9%) had pN2, and 10 (45%) had pN3 stages. On multivariate analysis, EUS N stage (positive) was associated with positive CnLNs (OR 2.86 [95%CI 1.08-7.58]). Among 342 patients who had R0 resection, the median follow-up was 3.6 years, and the median OS was 11.6 years. Among patients who received preoperative therapy, pT3/4 stage (HR 2.44 [1.27-4.69]; p = 0.01) and positive CnLN (HR 5.44 [2.36-12.52]; p < 0.001) were negatively associated with OS by multivariate analysis. Conclusions: CnLN metastases are uncommon in gastric cancer, and are associated with an adverse impact on OS. However, long-term survival is still possible in patients with positive CnLN whom underwent a D2 lymph node dissection. Larger multi-institutional studies are needed to determine if CnLN positivity requires a separate staging category.