A retrospective feasibility study of lymph node metastasis in submucosa gastric cancer based on the evaluation of pre- and intra-operative clinical-pathologic characteristics in two centers

Abstract Background. This paper investigates whether or not there are some preoperative predictors identifying lymph node metastasis (LNM) in patients with T1b gastric cancer and discusses the possibility of replacement by segmental gastrectomy (SG) or local gastrectomy (LG). Methods. This study included patients with gastric cancer who underwent radical gastrectomy between January 2012 and December 2018, as well as those diagnosed with pT1b. Independent risk factors of lymph node metastasis were determined using univariate and multivariable logistics regression among clinicopathological characteristics. ROC curve was established to predict lymph node metastasis based on external data for validation. Results. Among the 636 patients with pT1b gastric cancer as the internal training set, 168 (26.4%) had no lymph node metastasis. In addition, 3 cm or less in size (odds ratio [OR] 0.56, P<0.05), middle or upper portion (OR 0.64, P<0.05), differentiation (OR 0.40, P<0.001), without lymphatic-vascular invasion (LVI) (OR 0.39, P<0.001), and the negative status of HER2 (OR 0.46, P<0.005), were protective factors of LNM. A score was generated consisting of a middle portion and four other variables. ROC curve analysis on the external validation set revealed excellent discrimination as the area under the curve (AUC) was 0.815. The frequency of lymph node metastasis was 0% with all five protective factors. Conclusions. Based on this retrospective study, T1b gastric cancer of the middle part of the stomach which is 3 cm or less in size, differentiated-type, negative HER2 status, and without lymphatic-vascular invasion might indicate pylorus-preserving gastrectomy due to lack of lymph node involvement. Trial registration. The study is retrospectively registered.