Hypofractionated Radiotherapy (25 Gy/5) for Rare Superior Vena Cava Invasion by Papillary Thyroid Carcinoma: A Case Report.

Papillary thyroid carcinoma (PTC) typically carries an excellent prognosis with high survival rates and indolent behavior in most patients. Direct invasion or tumor thrombus extending into the great veins of the neck, including the superior vena cava (SVC), is exceptionally rare. We present the case of an 84-year-old woman with PTC complicated by SVC invasion and partial luminal obstruction. She was diagnosed with pT4aN1 PTC, initially managed with thyroidectomy, two courses of I-131 therapy, neck dissection for residual disease, and adjuvant external beam radiotherapy (EBRT). This was followed by years of indolent disease until mediastinal nodal progression with SVC invasion and occlusion of the left subclavian and internal jugular veins. The patient declined surgery and endovascular intervention but accepted a short course of palliative EBRT with 25 Gy in 5 fractions. Short-course palliative EBRT resulted in significant radiographic improvement over the course of a year without hemorrhagic complications. This case provides novel information about the indolent natural history of PTC even with SVC invasion and the potential utility of moderately hypofractionated palliative EBRT in this setting.