External Beam Radiation Therapy in Mediastinal Metastasis of Radioiodine-Refractory Papillary Thyroid Carcinoma: A Case Report

External beam radiation therapy (EBRT) for mediastinal metastasis of papillary thyroid carcinoma is challenging because of the radioresistance of the cancer cells and surrounding vital organs. A 45 year-old male was diagnosed with mediastinal metastasis of refractory papillary thyroid carcinoma based on 18F-Fluordeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) scan results. He received EBRT with the Volumetric Modulated Arc Therapy (VMAT) technique that gave very satisfying results to prevent airway obstruction and improve his symptoms. The total radiation dose was 50 Gy in 25 fractions over five weeks. One year after radiation therapy, the evaluation showed a good local and clinical response with no late toxicities. This case presentation offers important evidence for EBRT on treating a high risk, unresectable and metastatic papillary thyroid carcinoma where conventional therapy was not successful to control tumor progression.