Pneumothorax during lenvatinib treatment for hepatocellular carcinoma with lung metastasis.

Lenvatinib is an inhibitor of tyrosine kinases, such as vascular endothelial growth factor receptor and fibroblast growth factor receptor, and was first approved for use in thyroid cancer in 2015 in Japan. Additional approval was given in March 2018 for its use as a first-line treatment for advanced or unresectable hepatocellular carcinoma. Herein, we report a case of pneumothorax during lenvatinib treatment for multiple lung metastases of hepatocellular carcinoma in a 71-year-old man. Although the development of pneumothorax during treatment with anticancer agents for lung metastases is well-known, this is the first report of pneumothorax induced by lenvatinib during treatment for lung metastases of hepatocellular carcinoma.