Lung cavitation in patients with anaplastic thyroid cancer treated with lenvatinib

Background: Anaplastic thyroid cancer (ATC) is a rare malignancy with a poor prognosis. It accounts for 1-2% of all thyroid cancers. Lenvatinib is an orally administered inhibitor of vascular endothelial growth factor receptor (VEGFR)-1,-2, and-3, fibroblast growth factor receptor (FGFR)-1 to-4, platelet-derived growth factor receptor (PDGFR)-alpha, rearranged during transfection (RET), and KIT. There have been cases of pneumothorax caused by lung cavitation and collapse after administration of lenvatinib in ATC with lung metastasis. In this study, we investigate lung cavitation during treatment with lenvatinib in ATC patients with lung metastasis. Methods: All ATC patients with lung metastasis treated at our hospital with lenvatinib between November 2015 and May 2021 were selected from our electronic medical records. The primary objective was to determine the incidence of cavitation of lung metastasis of ATC in patients treated with lenvatinib. The secondary objective was to evaluate prognostic factors in ATC patients with lung metastasis treated with lenvatinib. Results: We identified 26 patients treated with lenvatinib for ATC with lung metastasis. Of these, 12 (46.2%) had cavitation with lung metastasis during lenvatinib treatment. The median overall survival (OS) was 128 days (79-228 days), and the cavitation (+) group had significantly longer OS than the cavitation (-) group [186 days (117-355 days) vs. 89 days (59-179 days), P=0.033]. Kaplan-Meier survival curves indicated a significant difference in OS was observed between the two groups (P=0.0293). Univariate analysis demonstrated lung cavitation was a significant prognostic factor (hazard ratio: 0.38, 95% CI: 0.16-0.93) Conclusions: Lung cavitation occurred in 46.2% of patients treated with lenvatinib for ATC with lung metastasis. Patients who developed lung cavitation had a significantly better prognosis than those who did not.