Breast surgical oncology is a rapidly evolving field with significant advances shaped by practice-changing research. Three areas of ongoing controversy are (1) high rates of contralateral prophylactic mastectomy (CPM) in the United States despite uncertain benefit, (2) indications for and use of neoadjuvant chemotherapy (NACT) and endocrine therapy (NET), and (3) staging and treatment of the axilla, particularly after neoadjuvant systemic therapy. We discuss the patient populations for whom CPM may or may not be beneficial, indications for NACT and NET, and the trend toward de-escalation of locoregional axillary treatment.