Prognostic Role of Nodal Skip Metastasis in Thoracic Esophageal Squamous Cell Carcinoma: A Large-Scale Multicenter Study.

Background: Nodal-skip metastasis (NSM) is found in esophageal squamous cell carcinoma (ESCC), but its prognostic role is controversial. This study aimed to investigate the prognostic value of NSM for thoracic ESCC patients.

Methods: Categorization of NSM was according to the N groupings of Japan Esophagus Society (JES) staging system, which is dependent on tumor location. Using the Kaplan-Meier method and Cox-regression analysis, this study retrospectively analyzed the overall survival (OS) for 2325 ESCC patients after radical esophagectomy at three high-volume esophageal cancer centers. Predictive models also were constructed.

Results: The overall NSM rate was 20% (229/1141): 37.4% in the in upper, 12.9% in the middle, and 22.2% in the lower thoracic ESCC. The patients with NSM always had a better prognosis than those without NSM. Furthermore, NSM was an independent prognostic factor for thoracic ESCC patients (hazard ratio [HR], 0.633; 95% confidence interval [CI], 0.499-0.803; P < 0.001). By integrating the prognostic values of NSM and N stage, the authors proposed the new N staging system. The categories defined by the new N staging system were more homogeneous in terms of OS than those defined by the current N system. Moreover, the new N system was shown to be an independent prognostic factor also for thoracic ESCC patients (HR, 1.607; 95% CI, 1.520-1.700; P < 0.001). Overall, the new N system had slightly better homogeneity, discriminatory ability, and monotonicity of gradient than the current N system.

Conclusions: This study emphasized the prognostic power of NSM and developed a modified node-staging system to improve the efficiency of the current International Union for Cancer Control (UICC)/American Joint Committee on Cancer (AJCC) N staging system.