The study is restricted to patients having had primary systemic chemotherapy for stage II and III breast cancer. Participation in a preoperative chemotherapy trial investigating anthracycline and taxane based regimen is allowed, but not mandatory for all patients. Patients must have significant remaining tumor tissue in the breast and/or axillary lymph node. This implies resistance to further chemotherapy and a clinically relevant risk for relapse. Bisphosphonates have a distinct mechanism of action and have demonstrated efficacy in the treatment of breast cancer with metastasis to the bone as well as adjuvant treatment after surgery of primary breast cancer. The 3rd generation bisphosphonate zoledronic acid has a favorable toxicity profile and can be conveniently given to patients over a long term period.