 This is a retrospective medical record abstraction study. It is a review and evaluation of up to 300 metastatic breast cancer patients treated with Abraxane or other taxanes such as paclitaxel and docetaxel to determine the overall cost of care for Abraxane compared to other taxanes in the first-line metastatic cancer setting and the cost of care for Abraxane compared to other taxanes when broken down by individual components of cost. In addition, the investigators will review the following patient outcomes: response rate, duration of therapy, toxicity, and survival. 