Breast cancer is the most common malignancy in women in the United States and is second only to lung cancer as a cause of cancer death. The overall management of breast cancer includes the treatment of local disease with surgery, radiation therapy, or both, and the treatment of systemic disease with cytotoxic chemotherapy, endocrine therapy, biologic therapy, or combinations of these. The NCCN Guidelines specific to management of large clinical stage II and III tumors are discussed in this article. These guidelines are the work of the members of the NCCN Breast Cancer Panel. Expert medical clinical judgment is required to apply these guidelines in the context of an individual patient to provide optimal care. Although not stated at every decision point of the guidelines, patient participation in prospective clinical trials is the preferred option of treatment for all stages of breast cancer.