The Prognostic Importance of the Number of Dissected Lymph Nodes After Induction Chemoradiotherapy for Esophageal Cancer

Background. Analyses of adequacy of lymph node dissection during resection of esophageal cancer are based on patients who have not undergone induction chemoradiotherapy. We sought to determine the minimum number of dissected lymph nodes necessary to ensure adequate staging after induction chemoradiotherapy. Methods. A prospectively maintained thoracic surgery database was queried to identify consecutive patients undergoing postinduction esophagectomy from 1996 to 2010. Cox proportional hazard and recursive partitioning survival analyses were performed. Results. Complete lymph node data were available for 395 patients. Mean age was 59.5 years, and 64 patients (16%) were female. The median number of dissected lymph nodes was 8 (range, 0 to 63). When pathologic (p) T stage, pN stage, and the number of dissected lymph nodes were used as predictors, only pN stage (odds ratio, 1.3; 95% confidence interval, 1.2 to 1.7) and age (odds ratio, 1.03; 95% confidence interval, 1.01 to 1.04) independently predicted survival. Recursive partitioning was performed on 262 pN0 patients using T stage and the number of dissected lymph nodes as predictors. No pN0 patient with 28 lymph nodes dissected died during follow-up. For patients with fewer than 28 lymph nodes dissected, the next prognostic factor was T stage. For pT1-2 N0 patients, the number of lymph nodes dissected did not affect survival. For pT3-4 N0 patients, a significant survival decrement was noted for patients with fewer than 7 lymph nodes dissected compared with those with more than 7 lymph nodes dissected. Conclusions. T stage determines prognosis in postinduction pN0 patients with fewer than 28 lymph nodes evaluated. Postinduction pT3N0 patients with fewer than 7 lymph nodes evaluated are understaged. (C) 2015 by The Society of Thoracic Surgeons