Preoperative neoadjuvant targeted therapy with lenvatinib for inoperable thyroid cancer

Rationale: Neoadjuvant chemotherapy (NAC) with lenvatinib for inoperable thyroid cancer has not been established. We have previously reported a case of NAC in 2020. Here, we report 5 cases of thyroid cancer treated with NAC from 2019 to 2021, including 3 cases of inoperable differentiated thyroid cancer, 1 case of anaplastic thyroid cancer, and 1 case of concomitant differentiated thyroid cancer and anaplastic thyroid cancer. Patient concerns and diagnosis: Four patients were pathologically diagnosed with thyroid cancer by cytology or biopsy, and 1 patient was diagnosed with follicular neoplasm. These patients had pleural, laryngeal, and esophageal invasion, and radical surgery would have required an extended operation and increased surgical risks. Interventions: Five patients with thyroid cancer displaying invasion of adjacent organs who were inoperable were preoperatively treated with lenvatinib alone; they underwent surgery when the tumor stopped shrinking. Outcomes: The best response was achieved after 1.7 to 4.7 months (average 2.9 months) of lenvatinib treatment, and the dose was reduced due to the occurrence of adverse events. Surgery was successfully performed when the tumor stopped shrinking. Conclusion: The prognosis of patients with inoperable thyroid cancer is poor; however, patients can undergo surgery safely after NAC treatment with lenvatinib. We hope that NAC will be considered as a treatment option for advanced thyroid cancers and serve as a precedent for safe treatment. This can be a new treatment option to eliminate unresectable thyroid cancers.