Effectiveness of Vandetanib for unresectable medullary thyroid cancer

Surgical therapy is the main strategy for medullary thyroid cancer, but there is no effective therapy for resectable advanced cases. Vandetanib is a once-daily oral inhibitor of RET kinase, vascular endothelial growth factor receptor, and epidermal growth factor receptor signaling. We experienced a case medicated by Vandetanib for medullary thyroid cancer. A 55-year-old female was diagnosed with medullary thyroid cancer by aspiration cytology of a thyroid tumor and needle biopsy histology. Since FDG-PET showed multiple bone metastases, she was treated with Vandetanib. Serum calcitonin and carcinoembryonic antigen decreased after withdrawal of the medication, and US showed decreased size of the thyroid tumor and cervical lymph nodes similarly. Since PET-CT showed decreased accumulation into these nodules, she was judged to have responded to the treatment. Though Vandetanib is a first-line TKI for unresectable medullary thyroid cancer, the purpose of this therapy is to control progression of the cancer.