Abstract
INTRODUCTION: Thymic epithelial tumors (TETs), encompassing thymomas and thymic carcinomas, are rare malignancies originating from thymic epithelial cells. This study aimed to characterize tumor-infiltrating immune cells (TIIC) within the tumor microenvironment (TME) and evaluate their prognostic significance in TETs. METHODS: We retrospectively analyzed 125 patients with surgically resected TETs (2009-2021). Immunohistochemical staining of tumor specimens was performed to assess TIIC distribution, with significant associations between immune markers and survival outcomes evaluated using Cox regression. RESULTS: Among the analyzed markers, CD20, CD204, CD206, and CD47 emerged as potential predictors for disease-free survival (DFS), while CD20 and CD204 showed prognostic relevance for overall survival (OS). Specifically, stromal CD20+ TIIC density was independently associated with prolonged DFS(HR=4.74, 95% CI(1.673-13.434), P=0.003) and OS (HR=5.086, 95% CI(1.391-18.594), P=0.014), whereas elevated CD204+ TIIC infiltration correlated with reduced DFS(HR=0.154, 95% CI(0.043-0.547), P=0.004) and OS(HR=0.169, 95% CI(0.056-0.607), P=0.002). CONCLUSION: These findings suggest that targeting M2 macrophage-driven immunosuppression may enhance therapeutic efficacy in TETs.