The purpose of this study is to test the ability of MR-guided Focused Ultrasound (MRgFU) to ablate breast adenocarcinoma in situ in a mouse model and induce a significant systemic and local anti-tumor immune response. Growing evidence indicates that ablation of cancer in vivo can cause immune stimulation and produce a potent anti-tumor response. An unmet need in the treatment of breast cancer is the reduction of morbidity, time and cost of chemotherapy and radiation therapy. We propose to address this problem by using MRgFU to ablate tumors in a mouse model of breast cancer and measure the immune response. The quantitative data from this study may provide an alternative treatment approach for breast cancer that is cheaper, faster and less toxic than current therapeutic options thereby accelerating FDA approval and implementation of MRgFU into clinical practice.