[A patient with multiple skin metastases from breast cancer responding to S-1 effectively under treatment with trastuzumab].

We report a case of a 52-year-old female with multiple skin metastases from breast cancer who responded to S-1. She underwent surgery of her right breast in March 2000 and the left in June 2006. Multiple skin metastases were later detected. As there was no hormone sensitivity, chemotherapy was selected. We started treatment with administration of S-1 at 120mg/day(4 weeks)and trastuzumab. Thoracic CT at the end of the three courses revealed the disappearance of the multiple skin metastases. No major side effects were seen. It was concluded from these findings that S-1 could be safely and effectively administered to advanced breast cancer patients.