Lymph Node Progression and Optimized Node Dissection of Middle Thoracic Esophageal Squamous Cell Carcinoma in the Latest Therapeutic Surgical Strategy.

Purpose: The aim of this study is to elucidate the optimized lymph node dissection range in middle thoracic (Mt) esophageal squamous cell carcinoma (ESCC) requiring surgery.
Patients and Methods: We retrospectively analyzed 165 ESCC patients who underwent surgery with curative intent between 2009 and 2016, including 99 (60%) with MtESCC. Preoperative chemotherapy was administered in more than 80% of cStage II/III MtESCC patients. The rates of pathological and potential metastasis (representing recurrences) to lymph nodes and prognosis (median follow-up 52 months) were clarified. Lymph node dissection efficacy was assessed by calculating the efficacy index (EI) for each lymph node.
Results: No. 2R had the highest rate of metastasis, with frequencies of 13/38/46% in cStage I/II/III, respectively, with the highest EI in MtESCC. Recurrences were seen in about 2-10% in the regional (nos. 1, 2L, 4R, and 10) and extraregional lymph nodes (paraaortic lymph node). The EI of lymph nodes was found to exhibit the highest score of 15 for no. 2R, followed by 11.5 for no. 17. The 5-year overall survival (OS) in MtESCC patients who underwent no. 2R lymph node dissection was 73.8%, while those who did not undergo no. 2R dissection did never reach 5-year OS (P = 0.002).
Conclusions: Meticulous lymph node dissection of no. 2R is the most important for long-term survival, and mandatory with the highest priority in MtESCC.