Radioactive Iodine-Refractory Differentiated Thyroid Cancer with Brain Metastasis: A Clinical Case Report

Abstract

Background: Differentiated thyroid cancer (DTC) is mainly treated with surgery and radioactive iodine (RAI), and typically has a favorable prognosis. Cases with distant metastasis often have a poorer prognosis and are at risk of becoming resistant to radioactive iodine. Progressive radioactive iodine-refractory DTC with brain metastasis is extremely rare and carries a grave prognosis, requiring a multimodal treatment approach. This report describes a typical clinical case, emphasizing diagnostic and therapeutic strategies.
Case Description: A 65-year-old female patient, diagnosed with papillary thyroid carcinoma, underwent total thyroidectomy and received four RAI treatments (total dose: 600 mCi) for lung and left 7th rib metastases. The patient was confirmed RAIrefractory and subsequently developed local recurrence and progressive brain metastasis during follow-up. Systemic therapy with lenvatinib and whole brain radiotherapy were administered.
Results: After one year of treatment, the brain lesions reduced in size, thyroglobulin levels progressively decreased, and the patient remained clinically stable.
Conclusion: RAI-refractory DTC with brain metastasis is rare and associated with a poor prognosis. Systemic therapy combined with localized treatment modalities can effectively control disease progression