Medullary thyroid cancer in the era of tyrosine kinase inhibitors: to treat or not to treat--and with which drug--those are the questions.

CONTEXT: Medullary thyroid cancer (MTC) is a rare form of thyroid cancer comprising approximately 4% of all thyroid cancers. The majority of patients have a relatively good prognosis; however, a subgroup of patients will require systemic therapy. Large phase III randomized trials led to the approval of two drugs--vandetanib and cabozantinib--for progressive or symptomatic MTC. The decision regarding which drug to initiate first is not entirely clear and is a common concern amongst treating physicians.

EVIDENCE ACQUISITION AND SYNTHESIS: A review of the literature in English was conducted, and data were summarized and integrated into a decision matrix.

CONCLUSIONS: The decision regarding which drug to initiate first for progressive MTC should be based on a careful review of the medical history, physical examination findings, medication list, electrocardiogram, laboratory results, and tumor characteristics. It is necessary to consider the relative contraindications when choosing which drug to initiate first.