Prognostic Value of Lymph Node Yield on Overall Survival in Esophageal Cancer Patients: A Systematic Review and Meta-analysis

Abstract

OBJECTIVE: This meta-analysis determines whether increased lymph node yield improves survival in patients with esophageal cancer undergoing esophagectomy with or without neoadjuvant therapy. BACKGROUND: Esophagectomy involves resection of the esophagus and surrounding lymph nodes, which are commonly the first stations of cancer spread. The extent of lymphadenectomy during esophagectomy remains controversial, with several studies publishing conflicting results, especially in the era of neoadjuvant therapy. METHODS: An electronic literature search was undertaken using Embase, Medline, and the Cochrane library databases (2000 to 2017). Articles with esophageal cancer patients undergoing esophagectomy with lymphadenectomy and investigating the effects of low and high lymph node yield on overall survival and disease-free survival were included. Meta-analysis of data was conducted using a random effects model. If the study divided the cohort into multiple groups based on lymph node yield, survival was compared between the lowest and highest lymph node yield groups. In addition to analysis of the entire cohort, subset analysis of only those patients receiving neoadjuvant therapy was also performed. RESULTS: A total of 26 studies were included in this meta-analysis with a follow-up ranging from 15 to 94 months. For the analysis of overall survival, 23 studies were included. A meta-analysis showed that overall survival significantly improved in the high lymph node yield group [hazard ratio (HR) = 0.81; 95% confidence interval (95% CI) = 0.74-0.87; P < 0.01]. In the 10 studies describing disease-free survival, this was significantly improved in the high lymph node yield group (HR = 0.72; 95% CI = 0.62-0.84; P < 0.01). Subset analysis of neoadjuvant-treated patients demonstrated a survival benefit of high lymph node yield on overall survival (HR = 0.82; 95% CI = 0.73-0.92; P < 0.01). CONCLUSION: This meta-analysis demonstrates the benefit of an increased lymph node yield from esophagectomy on overall and disease-free survival. In addition, a survival benefit of a high lymph node yield was demonstrated in patients receiving neoadjuvant therapy followed by esophagectomy.