Postoperative Survival Effect of Examined Lymph Node Count in Node-Negative Esophageal Carcinoma

Abstract

Background
 A limited lymphadenectomy may make patients with esophageal squamous cell carcinoma (ESCC) at risk for missing occult nodal disease. This study aimed to determine an effective threshold of lymph nodes (LNs) for evaluation of the quality of lymphadenectomy and discuss the impact of adjuvant chemotherapy on pN0 patients. 
 Methods
 Patients treated surgically for ESCC between 2010 and 2018 in Sichuan Cancer Hospital were included. NPV (Negative Predictive Value) based on a beta-binomial distribution was developed to assess the confidence of node-negative disease. Kaplan-Meier curves were plotted to compare survival differences among groups. 
 Results
 When patients had >21 LNs examined, the probability of false-negative findings was estimated at <10%, and NPV was estimated at a high level (>86.5%). For patients with LNs removed ≤21, 5-year OS (or DFS) in postoperative chemotherapy group vs that in surgery group was 65.3% vs 54.6%, p = 0.041 (or 59.2% vs 46.6%, p = 0.033). But for patients with >21 LNs, there were no statistical differences (p = 0.683 for OS or p = 0.942 for DFS). 
 Conclusion
 Only pN0 patients who were at high risk of occult lymph node metastasis (examined LNs ≤21) could benefit from postoperative chemotherapy.