Supplementary Material for: Postoperative Intensity-Modulated Radiotherapy Improved Survival in Lymph Node-Positive or Stage III Thoracic Esophageal Squamous Cell Carcinoma

<b><i>Background:</i></b> The aim of this study was to retrospectively analyze the effect of postoperative intensity-modulated radiotherapy (IMRT) on recurrence and survival in lymph node-positive or stage III thoracic esophageal squamous cell carcinoma (TESCC) patients, and evaluate its role in TESCC therapy. <b><i>Methods:</i></b> We enrolled 538 patients who underwent radical resection with (S + R) or without (S) postoperative IMRT. The median total postoperative IMRT dose was 60 Gy. The Kaplan-Meier method, log-rank test, and chi-square test were used for survival rate calculation, univariate analysis, and sites of failure analysis, respectively. <b><i>Results:</i></b> The 5-year overall survival (OS) and disease-free survival rates were 32.7 and 27.3%, respectively. The 5-year OS rates of lymph node-positive S and S + R patients were 28.4 and 38.8%, respectively (p &lt; 0.001). The 5-year OS rates of stage III S and S + R patients were 24.0 and 38.0%, respectively (p = 0.001). Postoperative IMRT resulted in significantly decreased intrathoracic and supraclavicular recurrence, and obviously delayed median local recurrence and systemic metastases. Systemic metastases increased following postoperative IMRT. <b><i>Conclusion:</i></b> Postoperative IMRT reduces local recurrence and improves survival in lymph node-positive or stage III TESCC patients, providing a rationale for selection criteria for postoperative IMRT in TESCC.