Achievement of pathologic complete response is important prognosticator to predict long term outcome in triple negative cancer. The efficacy of adding 4 cycles of cisplatin (CDDP4) is to be investigated whether addtional pathologic complete response is achieved for those triple negative breast cancer patients who recieved 4 cycles of adriamycin with cyclophosphamide(AC4) but did not reach clinical complete response during the course of neoadjuvant therapy.