Prognostic role of lymph node micrometastasis in pN0 esophageal cancer: A meta-analysis

Background: To further identify the association between the lymph node micrometastasis (LNM) and long-term survival among pN0 esophageal cancer patients receiving the surgery. Methods: Several databases were searched for relevant studies up to June 22, 2023. The primary and secondary outcomes were separately overall survival (OS) and relapse-free survival (RFS) and hazard ratios (HRs) with 95% confidence intervals (CIs) were combined. Subgroup analysis based on pathological type and source of HR was further performed. All statistical analyses were conducted by STATA 15.0 software. Results: A total of 20 studies involving 1830 pN0 patients were included in this meta-analysis. The pooled results demonstrated that the presence of LNM indicated significantly worse OS (HR = 2.19, 95% CI = 1.77-2.70, P < .001) and RFS (HR = 2.15, 95% CI = 1.65-2.80, P < .001). Besides, subgroup analysis for the OS and RFS stratified by the pathological type (squamous cell carcinoma vs mixed esophageal cancer) and source of HR (reported vs estimated) further identified the significant relationship of LNM with prognosis in surgical esophageal cancer. Conclusion: The presence of LNM indicated significantly poorer long-term survival among operated pN0 esophageal cancer patients. LNM could serve as a novel and reliable prognostic indicator in surgical esophageal cancer.