Complete response to low-dose sorafenib in a patient with metastatic renal cell carcinoma: A case report.

We present a case of a patient with metastatic renal cell carcinoma (mRCC) who was treated solely with low-dose sorafenib and achieved a complete response (CR). A 79-year-old man with cytokine-refractory mRCC involving the lung, abdominal wall and lymph nodes was treated with low-dose sorafenib (400 mg/day) as a second-line therapy. Five months into treatment, CR was confirmed by follow-up computed tomography. No severe adverse events were observed and sorafenib treatment was continued without appearance of new lesions. Although sorafenib has been approved for mRCC treatment, complete clinical recovery is uncommon and has rarely been described. In this case, low-dose sorafenib appears to be sufficient for achieving CR while suppressing toxicity. Furthermore, long-term continuous administration induces the patient to obtain disease stabilization. However, considering toxicity and treatment costs, it is debatable whether treatment should be discontinued or sustained after CR.