Prognostic Significance of the Number and Extent of Metastatic Lymph Nodes in Patients with Esophageal Cancer: Comparison of the Union for International Cancer Control 8th Edition and Japan Esophageal Society Japanese Classification of Esophageal Cancer 11th Edition Classifications for Esophageal Cancer

Background: The tumor, node, metastasis staging system of the Union for International Cancer Control (UICC) has been used worldwide for esophageal cancer, and, in Japan, the Japan Esophageal Society Japanese Classification of Esophageal Cancer (JES) has also been used; however, there is a big difference between the two classifications with regard to node staging. We hypothesized that these two node staging systems may lead to different outcome predictions in terms of tumor location. Methods: This study enrolled 409 patients who underwent esophagectomy at Keio University Hospital, Tokyo, Japan, between January 2005 and December 2017. We included those who underwent R0 or R1 resection or esophagectomy with additional organ excision, and excluded those who underwent salvage surgery. Thereafter, we investigated how the number or spread of metastatic lymph nodes affected the prognosis. Results: For all 409 patients, the 5-year overall survival rate was 64.1% and the 5-year recurrence-free survival rate was 58.4%. The concordance indices were 0.756 for UICC 8th edition pathological node staging and 0.732 for JES 11th edition pathological node staging (p = 0.06). Based on tumor location, the difference in the concordance indices between these two classifications was greatest for lower thoracic esophageal tumors (p = 0.02). Conclusions: For all patients, the UICC 8th edition node staging system tended to reflect survival more precisely than that of the JES 11th edition. For lower thoracic esophageal tumors in particular, the former node staging system could be more useful.