The Number of Lymph Nodes Removed Predicts Survival in Esophageal Cancer: An International Study on the Impact of Extent of Surgical Resection

Objective: Surveillance, Epidemiology and End Results (SEER) data indicate that number of lymph nodes removed impacts survival in gastric cancer. Our aim was to study this relationship in esophageal cancer. Methods: The study population included 2303 esophageal cancer patients (1381 adenocarcinoma, 922 squamous) from 9 international centers that had R0 esophagectomy prior to 2002 and were followed at regular intervals for 5 years or until death. Patients treated with neoadjuvant or adjuvant therapy were excluded. Results: Operations consisted of esophagectomy with (1700) and without (603) thoracotomy. Median number of nodes removed was 17 (IQR 10-29). There were 508 patients with stage I, 853 stage II, and 942 stage III. Five-year survival was 40%. Cox regression analysis showed that the number of lymph nodes removed was an independent predictor of survival (P < 0.0001). The optimal threshold predicted by Cox regression for this survival benefit was removal of a minimum of 23 nodes. Other independent predictors of survival were the number of involved nodes, depth of invasion, presence of nodal metastasis, and cell type. Conclusions: The number of lymph nodes removed is an independent predictor of survival after esophagectomy for cancer. To maximize this survival benefit a minimum of 23 regional lymph nodes must be removed.