Strategies of nodal staging of the TNM system for esophageal cancer

The 8^th edition of UICC/AJCC TNM staging for esophageal cancer will start in use since 2018. The nodal staging in this version of TNM system remains unchanged from the 7^th edition that based on the number of lymph nodes (LN) involved, except the limited revision of the regional LN map. In this review, N staging revision was evaluated from its initially simple definition of negative (N0) and positive (N1) LN(s) to the current positive node number based proposal. Meanwhile the disadvantages of current N staging were discussed. The refined nodal staging system in view of the number of metastatic node stations was introduced; as well as the extent and station of metastatic node could better reflect the disease progression and prognosis. The controversy on N staging of esophagogastric junction cancer was also discussed. Other reported N staging associated elements including LN ratio and lymphatic vessel invasion were reviewed and evaluated.