Effect of the number of lymph nodes sampled on postoperative survival of lymph node-negative esophageal cancer

BACKGROUND. The presence of lymph node (LN) metastases in esophageal cancer has important prognostic and treatment implications. However, the optimal number of LNs that should be examined for accurate staging is controversial. In the current study, the association between survival and the number of LNs evaluated was examined in patients who underwent resection of lymph node-negative (American Joint Committee on Cancer [AJCC] TNM stage I-IIA) esophageal cancer. METHODS. All patients were identified who underwent surgery for lymph node-negative esophageal cancer between 1988 and 2003 from the Surveillance, Epidemiology, and End Results cancer registry. Patients were classified into 3 groups by the number of negative LNs sampled during surgery (≤10 LNs, 11-17 LNs, and ≥18 LNs). Esophageal cancer-specific survival was compared among these LN groups using Kaplan-Meier curves. Stratified and Cox regression analyses were used to evaluate the association between survival and the number of negative LNs after adjusting for potential confounders. RESULTS. A total of 972 patients were included in the study. Disease-specific survival rates increased with a higher number of negative LNs. The 5-year disease-specific survival rate was 55% among patients with ≤10 negative LNs, compared with 66% and 75%, respectively, for those with 11 to 17 negative LNs and ≥18 negative LNs. The number of negative LNs was found to be significantly associated with survival in analyses stratified by tumor status. On multivariate regression controlling for age, race/ethnicity, sex, histology, tumor status, and postoperative radiotherapy, a higher number of negative LNs was found to be independently associated with higher disease-specific survival. CONCLUSIONS. The presence of LN metastases in patients with esophageal cancer appears to have important prognostic and treatment implications. Data from the current study suggest that patients undergoing surgical resection for esophageal cancer should have at least 18 LNs removed.