Extent of Lymphadenectomy in Esophageal Cancer Surgery: Unresolved Issues in Prophylactic 3-Field Dissection.

Esophagectomy with regional lymphadenectomy is a central component of treatment for resectable esophageal cancer, particularly esophageal squamous cell carcinoma. Because esophageal cancer can spread longitudinally through the lymphatic system, the optimal extent of lymphadenectomy has long been debated, particularly regarding 2-field lymphadenectomy (2FL) and 3-field lymphadenectomy (3FL). However, historical changes in terminology and inconsistent definitions of these procedures have complicated the interpretation of the available evidence. This review summarizes the historical development of lymphadenectomy in esophageal cancer surgery and current perspectives on its appropriate extent. We highlight the evolving definitions of 2FL and 3FL in the Japanese Classification of Esophageal Cancer and their implications for interpreting previous studies. Previous studies have used inconsistent definitions of 2FL, ranging from limited mediastinal dissection to total mediastinal dissection, which limits the applicability of direct comparisons with 3FL. Under the current definition, 2FL includes cervical paraesophageal lymph node dissection, whereas 3FL essentially involves the additional dissection of the bilateral supraclavicular lymph nodes. Recent evidence, including meta-analyses and large multicenter retrospective studies, has not demonstrated a clear survival benefit of prophylactic 3FL over contemporary 2FL. Given these uncertainties, the current Japanese guidelines weakly recommend 3FL for upper and middle thoracic esophageal cancer. The ongoing randomized phase III JCOG2013 trial is expected to clarify the therapeutic value of prophylactic supraclavicular lymph node dissection. A precise understanding of procedural definitions is essential for interpreting the literature and determining the appropriate extent of lymphadenectomy in esophageal cancer surgery.