[Discussion of N staging category of the eighth edition of The AJCC Esophageal Cancer Staging System]

AJCC Esophageal Cancer Staging System, 8(th) edition will be implemented on January 1, 2018. The N staging in 8(th) edition of staging system remains following 7(th) edition based on the number of metastatic nodes, except the limited revision of the regional lymph node map. N staging revision was reviewed from the simple definition of negative (N0) and positive (N1) lymph node(s) to the positive node number based proposal (7(th) edition). The 7(th) edition staging system, especially the N staging, were proved with more advantages on distinguishing disease progression and predicting prognosis of the esophageal cancer. On other hand, the disadvantages of 7(th) edition N staging are discussed. The refined N staging based on the number of metastatic node station is introduced. The extent and station of metastatic node could better reflect the disease progression and prognosis according to our research. The controversy on N staging of esophagogastric junction cancer is discussed as well. Other reported N staging associated index including lymph node ratio, lymphatic vessel invasion and biomarkers are reviewed and evaluated.