Abstract
Intravenous immunoglobulin (IVIG) is used to treat various diseases and has anticancer effects that suppress metastases in animal models of sarcoma and melanoma. However, these effects have been observed in a limited number of clinical cases. We report the case of a patient with metastatic breast cancer in which long-term IVIG treatment stopped disease progression in the absence of salvage chemotherapy. The patient was treated with IVIG for the treatment of immune thrombocytopenia. Surprisingly, the lung and brain metastases were stabilized, and the patient achieved a progression-free interval of 29 months. More cases are needed to investigate and confirm the efficacy of IVIG in solid tumors in the future.