Lenvatinib as an urgent initial therapy in thyroid cancer with remarkable laryngotracheal invasion.

Objectives: In thyroid cancer with marked laryngotracheal invasion, life-threatening airway stenosis necessitates urgent procedures such as extensive curative surgery, tracheostomy, stenting, or laser bronchoscopy. These interventions are invasive and may significantly compromise quality of life. In anaplastic thyroid cancer (ATC), the delay during genetic testing turnaround time before initiating targeted therapy poses an additional therapeutic challenge. This study aimed to assess lenvatinib (LEN) as an initial and bridging treatment to rapidly alleviate airway stenosis and avoid emergency invasive interventions. Methods: This retrospective study analyzed 14 patients with remarkable laryngotracheal invasion among 69 thyroid cancer patients treated with multikinase inhibitor(s). All 14 patients received LEN as first-line or post-paclitaxel treatment. Response was assessed by CT imaging per RECIST 1.1, with particular attention to changes in tumor size and airway diameter. Symptom improvement and adverse events, such as fistula formation, were also recorded. Results: Of the 14 patients, 13 showed tumor reduction and airway improvement on initial CT post-LEN induction. Median response rate was 28.4%, with airway diameter improving by 15.9% on the initial CT. Airway symptoms resolved in a median of 3 days. One patient developed a tumor-tracheal fistula, managed with LEN dose adjustment. LEN was also successfully used as a bridging therapy before BRAF-targeted treatment in ATC cases. Conclusions: Initial LEN therapy rapidly alleviates airway stenosis in advanced thyroid cancer with laryngotracheal invasion, offering a non-invasive alternative to emergency procedures under careful monitoring for fistula formation. LEN is especially valuable as a bridging therapy during the genetic testing period in ATC.