Effective Lenvatinib Treatment Complicated With Secondary Tracheocutaneous Fistula In Patients With Advanced Anaplastic Thyroid Carcinoma

Anaplastic thyroid carcinoma (ATC) is a fatal disease with a poor prognosis. Lenvatinib is an oral multi-targeted tyrosine kinase inhibitor (TKI) which is approved in Japan for the treatment of ATC. Data of treatment response and adverse effects of lenvatinib in ATC patients is still relatively scarce, especially in non-Japanese patient populations. Here we report dramatic treatment effects of lenvatinib in two patients with stage IVc ATC, who later developed significant morbidities including tracheal perforation and fistula formation. Our cases demonstrate the efficacy and provide cautionary information for treatment of ATC. In treating advanced ATC patients with lenvatinib, close monitoring is highly recommended.