The metastatic lymph node number and ratio are independent prognostic factors in esophageal cancer

Objective The current American Joint Committee on Cancer staging system for esophageal cancer is based on lymph node location, irrespective of the number of involved and examined lymph nodes. Methods We enrolled 488 patients receiving primary curative resection without neoadjuvant therapy for esophageal cancer between 1995 and 2006. The importance of total resected lymph node number (TLN) and metastatic lymph node number (MLN) and ratio (MLR) on patient survival was investigated. Results The overall 3-year survival rate was 35.4%. The 3-year survival rate was equivalent among patients in N1 (23.3%), M1a (22.0%), and nonregional lymph node metastasis-related M1b (18.5%, p=0.321). No survival difference was noted between patients with TLN<15 or ≥15 (p=0.249). Both MLN and MLR significantly predicted patient survival. The 3-year survival rate was 52.3%, 29.2%, and 8.0% for patients with MLN=0, 1-3, and ≥4, respectively (p<0.001). For patients with MLR=0-0.2 or >0.2, the 3-year survival rate was 28.7% and 9.8%, respectively (p<0.001). However, survival rate differences were more evident when TLN was more than 15. Conclusions We recommend designating both regional and nonregional lymph nodes as N nodes. MLN and MLR, but not TLN, are prognostic factors in esophageal cancer.