New and emerging therapeutic options for thyroid carcinoma

The incidence of thyroid cancer has increased in the past few decades. Most patients with follicular cell–derived tumors present with well-differentiated carcinomas, and they have an excellent prognosis following treatment. Between 10% and 15% of tumors will mutate into more aggressive variants, such as tall-cell carcinoma and insular carcinoma. Some patients will present with poorly differentiated carcinomas requiring aggressive surgery and adjuvant therapy. The management plan for patients with thyroid carcinoma is based on the tumor type and prognostic risk factors. There is controversy regarding whether all thyroid cancers require treatment. In most cases, the initial treatment for differentiated thyroid cancers is surgical. Radioactive iodine (RAI) was established as adjuvant therapy more than 50 years ago, but data show that many patients do not respond to this therapy or develop RAI-refractory disease, which is associated with a poor prognosis. Until recently, there were no specific targeted systemic therapies available for patients with RAI-refractory thyroid cancer. The US Food and Drug Administration has recently approved 2 systemic agents for RAI-refractory disease: sorafenib and lenvatinib. These approvals have paved the way for the clinical development of other targeted therapies, with many showing promising results in patients with RAI-refractory disease.