The Impact of Two-field or Three-field Lymphadenectomy on Overall Survival in Middle and Lower Thoracic Esophageal Squamous Cell Carcinoma: An Observational Study

Inclusion Criteria: * 1\. Men and women aged 18-85 years * 2\. Histologically confirmed primary thoracic esophageal squamous cell carcinoma, * 3\. Staging PT1b-4A, N0-3, M0 AJCC eighth edition * 4\. Excluding lymph node dissection \< 15, (meeting the guideline criteria) * 5\. The tumor located in the lower middle thoracic. Exclusion Criteria: * 1\. Patients with a history of previous thoracic and abdominal surgery that may affect lymphatic reflux * 2\. Patients with distant metastasis confirmed by imaging * 3\. Patients with obvious surgical contraindications.