Novel therapies for thyroid cancer.

INTRODUCTION: New therapeutic options for both differentiated thyroid cancer (DTC) and medullary thyroid cancer (MTC) have opened up during the past few years, as the key role of tyrosine kinases in the pathogenesis of thyroid carcinoma has been proved. Recently, two tyrosine kinase inhibitors (TKIs) targeting VEGFR vandetanib (Caprelsa) and cabozantinib (Cometriq) have been approved for advanced MTC, whereas, sorafenib (Nexavar) has been accepted to treat late-stage of DTC. Their efficacy was demonstrated in Phase III studies, compared to placebo; each of them significantly prolonged the progression-free survival. AREAS COVERED: Common adverse reactions related to VEGFR blockade are hypertension, proteinuria, impaired wound healing, hemorrhage and thrombosis, and congestive heart failure. Fatigue, different gastrointestinal disturbances with diarrhea, appetite decrease and weight loss are observed in the majority of patients. Another frequent TKI side effect is thyroid-stimulating hormone increase secondary to inhibition of MCT8-dependent T3 and T4 uptake in pituitary. EXPERT OPINION: So far, no direct comparison of both treatment outcomes and toxicity between particular drugs has been carried out. The evidence-based medicine guidelines are necessary to precisely indicate what drug to use: more effective or less toxic and when to start the treatment.