Frequency and distribution pattern of lymph node metastasis after neoadjuvant chemoimmunotherapy for locally advanced esophageal squamous cell carcinoma

Background Currently, neoadjuvant chemoimmunotherapy (NCIT) is widely used in the perioperative treatment of esophageal squamous cell carcinoma (ESCC). However, the patterns of lymph node metastasis following this novel treatment approach remain poorly understood. The aim of this study was to elucidate the distribution and frequency of postoperative lymph node metastasis (LNM) after NCIT. Methods We retrospectively analyzed cases from March 2020 to March 2023 in our hospital and selected patients who underwent NCIT followed by R0 resection for esophageal cancer. A total of 257 patients with clinical stage T3N0 or T1-3N + thoracic esophageal cancer were included. The distribution and frequency of metastatic lesions in each lymph node station were recorded according to the Japan Esophageal Society (JES) staging system. Additionally, we analyzed the patterns of lymph node metastasis based on the location of the thoracic tumor. Results Among the 257 patients, 110 (42.8%) had pathologically positive lymph nodes postoperatively. Common sites of lymph node metastasis included station 107 (12.8%), station 106recR (11.7%), and station 7 (12.5%). The lymph node stations with lower metastasis rates were station 105, station 106tbL, and station 111, each with a metastasis rate of 2.3%. In upper thoracic (Ut) cases, station 106recR (23.7%) was the most common site of lymph node metastasis, while in middle thoracic (Mt) cases, station 107 (16.7%) had the highest metastasis rate, and in lower thoracic (Lt) cases, station 7 (17.6%) had the highest metastasis rate. Lymph node metastasis (LNM) was more likely to occur in station 101R in Ut and Mt cases than in Lt cases (13.2% and 8.6%; p < 0.01). Conclusions This study reveals the frequency and distribution patterns of lymph node metastasis following NCIT, highlighting the different patterns of lymph node metastasis based on tumor location. These findings can provide guidance for lymph node dissection during surgery.