Significant Amelioration of Tracheal Stenosis following Lenvatinib in a Patient Who Has Anaplastic Thyroid Carcinoma with Bronchomediastinal Infiltration: A Case Report

BACKGROUND Anaplastic thyroid carcinoma has an extremely poor prognosis, and no known drugs have exhibited acceptable efficacy. In recent years, novel anticancer tyrosine kinase inhibitors have been developed. We encountered a case of tracheal stenosis due to mediastinal and tracheal infiltration of anaplastic carcinoma for which lenvatinib exhibited remarkable effects; owing to this, airway management could be performed, even though the patient's condition was considered critical. CASE REPORT A 55-year-old man presented with locally advanced anaplastic thyroid carcinoma that was observed to have mediastinal infiltration. Tracheal stenosis due to infiltration of the trachea occurred, and the condition of the patient rapidly deteriorated. Radiation and chemotherapy consisting of cetuximab, cisplatin, and fluorouracil were ineffective, but his tracheal stenosis was relieved 2 weeks after initiation of lenvatinib, after which the patient could be discharged. However, the lenvatinib was ineffective for his liver, bone, and brain metastatic lesions, and the patient remained in a critical condition. CONCLUSION We encountered a case in which lenvatinib was effective for locally advanced anaplastic thyroid carcinoma, leading to an improvement in quality of life and a prolonged life. The drug was effective for the primary lesion, but mixed efficacy was noted for distant metastatic lesions.