Prognostic significance of the number of lymph nodes dissection in esophageal adenocarcinoma patients

Esophageal cancer (EC) is one of the most common malignancies in the world (1). As reported by the 2018 Global Cancer Statistics, there are approximately 572,034 EC patients and 508,585 EC-related deaths worldwide (1). EC can be mainly classified as two types, namely, squamous cell carcinoma and adenocarcinoma. Among them, esophageal squamous cell carcinoma (ESCC) is the most common subtype of EC in the world, but the incidence of esophageal adenocarcinoma has increased sharply rapidly in numerous western countries over the past few decades, which even surpasses that the incidence of ESCC in the United Kingdom (UK), the Netherlands, Ireland, New Zealand, the United States (US), Australia, Denmark, Canada, and Sweden (2-4). Esophageal adenocarcinoma is considered as one of the fatal digestive tract malignancies, with the 5-year survival rate of as low as 16% (5). Esophagectomy combined with lymphadenectomy has long been adopted as the main treatment for EC, but there is no consensus on the number and scope of lymph node dissection (LND) among surgeons (6,7). A large number of relevant studies mainly involve ESCC, however, the relationship between the LND number and the prognosis for esophageal adenocarcinoma remains unclear and should be explained in further studies (8-11). Some researchers believe that, expanding the scope and number of LNDs contributes to removing more hidden positive lymph nodes and provides more accurate information on pathological staging, thus bringing superior prognosis for patients (11-13). Nonetheless, other researchers consider that, LND has limited benefit for EC patients; as a result, it is unnecessary to expand the score and number of LND, and they believe that this approach will not only bring more benefits to the patients, but also result in increased surgical risks and postoperative complications (7,12,14)