Impact of pathologically assessing extranodal extension in the thoracic field on the prognosis of esophageal squamous cell carcinoma

Abstract Background This study aimed to elucidate the impact of extranodal extension, pathologically assessed according to new diagnostic criteria, on the prognosis of esophageal squamous cell carcinoma. Extranodal extension has been shown to be a prognostic indicator for head and neck cancers; however, its utility in esophageal squamous cell carcinoma has not been demonstrated. Methods We enrolled 174 consecutive esophageal squamous cell carcinoma patients who had undergone esophagectomy with lymph node dissection in the three fields. Extranodal extensions from all metastatic lymph nodes were pathologically classified into grades 1–3. Then, relationships between extranodal extension and clinicopathologic factors, including overall survival and recurrence-free survival were examined. Recurrence patterns in the thoracic and abdominal fields were also examined. Results Kaplan–Meier analyses showed that patients with grades 2 and 3 extranodal extension showed significantly poorer recurrence-free survival compared with those with intranodal involvement of esophageal squamous cell carcinoma cells ( P  = .0041 and P  = .0011, respectively). Patients with pN3b (newly defined in this study as including at least one lymph node with grade 2–3 extranodal extension regardless of region or number of metastatic lymph nodes) was associated with significantly shorter overall survival and recurrence-free survival ( P P  = .047; abdominal: P  = .15). Conclusion This study suggests that the extranodal extension grading system proposed in this study is a novel predictor of overall survival and recurrence-free survival in esophageal squamous cell carcinoma.