Impact of lymph node dissection on prognosis in esophageal squamous cell carcinoma patients undergoing neoadjuvant chemotherapy and immunotherapy followed by radical surgery.

e16149 Background: Currently, neoadjuvant chemoimmunotherapy (nCIT) is widely used in the perioperative treatment of esophageal squamous cell carcinoma (ESCC).In addition, nodal metastases decreased in frequency and changed in distribution after neoadjuvant therapy.This study aimed to examine the optimal strategy for lymph node dissection in patients with ESCC who underwent nCIT. Methods: We retrospectively analyzed cases from Feb 2020 to Sept 2023 in three hospitals and selected patients who underwent NCIT followed by R0 resection for ESCC.The hazard ratios (HRs) for disease-free survival (DFS) was calculated using the Cox proportional hazard model. the minimal number of lymph node(m-NLN) or least station of lymph node(l-SLN) were used to obtain the optimal breakpoint for predicting the endpoint event by the maxstat function in R. Results: In total, 149 patients were included.The estimated cut-off values for l-SLN and m-NLN were 8 and 20, respectively.The m-NLN > 20 was significantly associated with better DFS prognosis (HR = 0.29, 95% CI: 0.14, 0.60, p < 0.001), and l-SLN > 8 was also significantly associated with DFS prognosis (HR = 0.40, 95% CI: 0.20, 0.84, p = 0.015).The m-NLN was a significant prognostic factor in multivariate analyses.A subgroup analysis was conducted on m-NLN in patients undergoing postoperative immune maintenance.The m-NLN > 20 and < 40 was significantly associated with better DFS prognosis (HR = 0.29, 95% CI: 0.14, 0.60, p < 0.001). Conclusions: This cohort study revealed an association between the extent of LND and overall survival, suggesting the therapeutic value of extended lymphadenectomy during esophagectomy.A higher number of lymph node stations and lymph nodes sampled is associated with improved prognosis in patients undergoing nCIT. It is recommended to perform standard lymph node dissection involving at least 9 lymph node stations and 21 lymph nodes.Standard lymph node dissection involving 21 to 39 lymph nodes results in better outcomes for patients receiving postoperative immunotherapy. Multivariate analysis of influencing factors (Cox regression). Characteristic N Event N HR 1 95% CI 1 p-value Tumor size，cm ＜3 100 16 — — ≥3 49 15 1.81 0.80, 4.12 0.157 TRG 0-1 80 12 — — 2 30 7 1.36 0.40, 4.57 0.619 3 39 12 0.81 0.24, 2.73 0.734 Number of LN harvest ＞20 114 18 0.21 0.07, 0.63 0.005 Stations of LN ＞8 96 16 0.81 0.29, 2.31 0.699 Vascular invasion status YES 23 12 1.65 0.58, 4.63 0.346 Neural invasion status