The number of lymph nodes removed predicts survival in esophageal cancer: an international study on the impact of extent of surgical resection

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. 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. Operations consisted of esophagectomy with (1700) and without (603) thoracotomy. Median number of nodes removed was 17 (IQR10-29). 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. 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.