The Prognosis Value of Lymphatic Vessel Invasion in pN0 Gastric Cancer Patients with Insufficient Examined Lymph Nodes

Objectives To investigate the prognosis value of lymphatic vessel invasion (LVI) in pN0 gastric cancer patients with insufficient examined lymph nodes (ELNs). Methods Clinicopathologic and prognostic data of pN0 gastric cancer patients with insufficient ELNs who underwent radical surgery in our institution were retrospectively studied. Results Firstly, we confirmed that less than 16 but not less than 30 ELNs were insufficient ELNs in the present study. Of the 350 pN0 patients with < 16 ELNs, 64 patients (18.29%) had LVI. The overall survival (OS) of patients with LVI was significantly poorer than those without LVI. Multivariate analysis suggested that LVI was one of the independent factors predicting prognosis of pN0 patients with < 16 ELNs. Further analyses suggested that there were similar prognoses between pN0 patients with < 16 ELNs who had LVI and pN1 patients, and between pN0 patients with < 16 ELNs who had no LVI and pN0 patients with >= 16 ELNs, respectively. Therefore, we proposed a novel pN classification, in which LVI-positive pN0 gastric cancer with < 16 ELNs was classified as pN1 disease. Two-step multivariate analysis demonstrated that the novel pN classification was more suitable for prognostic assessment than the original one. Conclusions LVI is a powerful and independent prognostic factor for pN0 gastric cancer patients with < 16 ELNs, and node-negative gastric cancer with < 16 ELNs which had LVI should be considered as node-positive disease. LVI is an effective indicator identifying patients stage migration happens to in pN0 patients with < 16 ELNs.