Neoadjuvant Radiotherapy for Locally Advanced Unresectable Thymoma

Inclusion Criteria: * Aged ≥18 years and ≤75 years. * Histologically confirmed thymoma of Masaoka-Koga stage III-IV A. * Assessed as unresectable thymoma by a thoracic surgeon prior to treatment. * Eastern Cooperative Oncology Group (ECOG) performance status of 0-1. * No prior anti-thymoma treatment, including but not limited to systemic chemotherapy, radiotherapy, surgery, or immunotherapy. * Presence of at least one measurable lesion according to RECIST v1.1 criteria. * Cardiopulmonary function compatible with surgery. * Expected survival of \>3 months. * Comprehensive evaluation completed within 28 days before enrollment in the study, with a full blood cell test obtained within 15 days, demonstrating normal visceral organ function and normal bone marrow function. * Negative serum or urine pregnancy test for women of childbearing potential within 14 days before study enrollment. * Willingness of the patient to sign an informed consent form and to adhere to the specified follow-up schedule. Exclusion Criteria: * Histologically confirmed thymic neuroendocrine tumor. * Currently participating in an interventional clinical study that may affect this study, or having received other investigational drugs or devices within 4 weeks prior to the first treatment in this study. * Pregnant or breastfeeding women. * Previous history of thoracic radiotherapy. * Deemed unsuitable for three-dimensional conformal or intensity-modulated radiotherapy by a radiation oncology specialist. * History of allogeneic bone marrow or organ transplantation. * History of malignancies other than thymoma within the past 3 years, or untreated other primary malignancies. * Serious comorbidities that would affect the study treatment. * Any history or evidence of disease, treatment, or abnormal laboratory values that could interfere with the study results or prevent the participant from completing the study, or other situations deemed unsuitable for enrollment by the investigator.