Lenvatininb as Treatment for Naïve Patients with AggressiveThyroid Cancer Bone Metastases and Bad Performance Status

Lenvatinib is an oral multityrosine kinase inhibitor (TKI) with proven effectiveness in the treatment of radioactive iodine- (RAI-)refractory and/or unresectable differentiated thyroid carcinoma (DTC). The present study reports the case of a 41-year-old malewho underwent hemithyroidectomy in June 2015 due to a thyroid nodule withfine-needle aspiration follicular neoplasmcytology and no evidence of malignancy in the histopathological exam. Three years later, acute disabling clinical symptomsemerged, mainly high skeletal pain conditioned with an important performance status decrease. PET/CT scan displayed severalmetastatic bone lesions in this context, located in the vertebral bodies, sternum, ribs, iliac crest, right acetabulum, and bothnecks of the femur. Histological study and immunohistochemistry confirmed DTC metastases, as they were strongly positive forthyroglobulin and TTF-1. At this point, the patient was unfit for conventional management that would have includedcompletion of surgery and RAI treatment asfirst options. Thus, it was decided to start systemic treatment with TKI, Lenvatinib.Within thefirst week of treatment, the patient was almost asymptomatic and his performance status moved from 3 to 0. Thisallowed the patient to undergo resection of the thyroid gland remnant plus RAI treatment. Unfortunately, RAI refractoryillness was confirmed so Lenvatinib treatment should be continued in this case until the evidence of no further clinical benefit.Despite drug adverse events, the patient continues with treatment one year later, remaining asymptomatic and with normalfunctional capacity.