The 45th annual meeting of the American Society of Clinical Oncology took place on May 29–June 2 in Orlando, Florida. Important clinical and research data in the field of breast cancer presented during this prestigious meeting are reviewed in this material. The breast cancer sessions were marked by advances in prognostic and predictive markers, pharmacology, and, most notably, the treatment of metastatic breast cancer. A new class of drugs, the poly (ADP-ribose) polymerase (PARP) inhibitors, showed remarkable efficacy in the treatment of triple-negative breast tumors and BRCA1 and 2 associated tumours. New data confirmed that bevacizumab could be associated with different types of chemotherapy in the first-line treatment of metastatic breast cancer, with limited benefit in progression-free survival, but without improving overall survival. Long-term follow-up data confirmed the importance of urokinase tissue plasminogen activator/plasminogen activator inhibitor type I (uPA/PAI-1), as a prognostic factor for node-negative breast cancer patients. A large sentinel node study suggests that if a patient has a positive sentinel lymph node, axillary dissection remains the standard of care. Several studies investigated the influence of CYP2D6 inhibitors on the outcomes of patients with breast cancer receiving tamoxifen as adjuvant therapy.