Abstract
Anaplastic thyroid cancer is a fatal disease for which no effective therapeutic strategies exist. Lenvatinib, a tyrosine-kinase inhibitor that targets vascular endothelial growth factor receptor, has recently been approved in Japan for the treatment of patients with unresectable thyroid cancer including anaplastic thyroid cancer. Although lenvatinib, like the other tyrosine-kinase inhibitors, sunitinib and sorafenib, might also confer a risk of bleeding, fatal bleeding as a result of lenvatinib treatment for anaplastic thyroid cancer has not been described. A 61-year-old woman presented with a 7-cm mass in the right lobe of the thyroid, lymph node metastases to the neck and multiple lung metastases. Fine needle aspiration revealed that the tumor was anaplastic thyroid cancer. The TNM classification was T4aN1bM1, stage IVC. Shortly after local curative surgery, a tumor recurred in her neck that was treated with lenvatinib (24 mg/day). Nineteen days later, the common carotid artery ruptured and the lenvatinib was stopped. She received the best possible supportive care but died 40 days after stopping the lenvatinib. Autopsy findings showed that the tumor had invaded the adventitia of the common carotid artery at the region of the neck surgery, and an aneurysm had developed. However, the adventitia of the common carotid artery was preserved at the non-dissected area. Lenvatinib might confer risk for fatal bleeding in patients with recurrent anaplastic thyroid cancer after neck surgery, particularly with dissection around the common carotid artery.