Cross-Sectional Survey on Mediastinal Lymph Node Dissection in Lung and Esophageal Cancer: A Project of the Anatomy of the Border Consensus Meeting at the 37th Annual Meeting of the Japan Society for Endoscopic Surgery.

INTRODUCTION: Although mediastinal lymph node dissection is performed in both lung and esophageal cancer surgeries, the underlying concepts and indications may differ between these fields. This study aimed to clarify these differences through a nationwide questionnaire survey initiated by the 37th Annual Meeting of the Japan Society for Endoscopic Surgery. METHODS: A joint task force from the lung and esophageal surgery divisions developed a questionnaire focusing on four key areas: (i) lymph node dissection around the left recurrent nerve, (ii) subcarinal lymph node dissection, (iii) pulmonary ligament lymph node dissection, and (iv) en bloc lymph node dissection. The survey was distributed to certified core institutions across Japan. RESULTS: The response rates were 50.4% for lung cancer institutions and 57.0% for esophageal cancer institutions. In the esophageal division, dissection of the aforementioned lymph nodes was routinely performed in most core institutions. In contrast, practices in the lung division varied widely, particularly depending on tumor location. The concept of "sampling" was rarely recognized in esophageal surgery but was partially accepted in lung surgery. Furthermore, there was no uniform definition of "en bloc dissection" across either field. CONCLUSION: This cross-sectional survey revealed notable conceptual differences between lung and esophageal cancer divisions regarding mediastinal lymph node dissection, despite targeting the same anatomical regions. Additionally, significant variability was observed even within the lung division. These findings indicate a lack of standardized consensus in Japan and highlight the need for ongoing cross-disciplinary dialog and consensus building.