The prognostic importance of the number of involved lymph nodes in esophageal cancer: Implications for revisions of the American Joint Committee on Cancer staging system

Objective: The American Joint Committee on Cancer (AJCC) staging system for esophageal cancer is controversial because it relies on arbitrary definitions of the anatomic location of lymph nodes to establish N and M status. It has been proposed that the number of involved lymph nodes may better predict survival. We reviewed our experience to determine the prognostic impact of the number of involved nodes and the extent of lymphadenectomy on the current staging system. Methods: Records of all patients who underwent resection of previously untreated adenocarcinoma and squamous cell carcinoma of the esophagus and gastroesophageal junction were reviewed. Overall survival according to the AJCC staging system and the number of involved lymph nodes was analyzed by the method of Kaplan and Meier and by recursive partitioning methods. Results: Data were available on 336 patients operated on between January 1996 and September 2003. Recursive partitioning analysis using AJCC staging variables reproduced the AJCC staging system. When the number of involved lymph nodes is added, patients with more than 4 involved lymph nodes have survival similar to that of patients with M1 disease, and patients with no involved lymph nodes have the best prognosis. Recursive partitioning analysis identified 18 lymph nodes as the minimal number required for accurate staging. In patients who have 18 or more lymph nodes removed, survival is only predicted by the presence of nodal involvement and M1 disease. Conclusion: Our analysis suggests that revisions of the current AJCC staging system for esophageal cancer should include N staging based on the number of involved lymph nodes and minimal requirements for the extent of lymphadenectomy.