| Objective: A limited lymphadenectomy may make patients who underwent surgery for esophageal squamous cell carcinoma(ESCC)at risk for missing occult nodal disease.This study aimed to determine an appropriate number of lymph nodes(LNs)examined for patients with declared node-negative ESCC.Methods: Patients treated surgically for ESCC between 2010 and 2018 in Sichuan Cancer Hospital were included.A beta-binomial distribution was used to estimate the probability of occult nodal disease,and Nodal Staging Score(NSS)was developed to assess the confidence of node-negative diseases.A Cox regression model with stepwise selection was used for univariate and multivariate analyses.Propensity-score matching(PSM)was used to reduce selection bias.Kaplan-Meier curves were plotted to compare survival differences among groups.All tests of statistical significance were 2-sided.Results: To develop our model,2722 patients with ESCC were divided into p N0(n = 1261)and p N+(n = 1461)groups.When patients had 21 LNs examined,the probability of false-negative findings was estimated at less than10%,and NSS was estimated at a high level(>86.5%).After propensity-score matching,682 p N0 patients were selected for further analysis.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 significant statistical differences(p = 0.683 for OS or p = 0.942 for DFS).Conclusion: Our study recommends 21 lymph nodes examined as an effective threshold for evaluation of the quality of lymphadenectomy or prognostic stratification for patients with declared node-negative esophageal squamous cell carcinoma.Postoperative chemotherapy could bring an appreciable benefit for p N0 patients who were at high risk of occult lymph node metastasis(examined LNs ≤21),but it might be ineffective for patients with a relatively adequate lymph node examination(examined LNs >21). |
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