Shifting the Paradigm: The Transformative Role of Neoadjuvant Therapy in Early Breast Cancer

Simple Summary Neoadjuvant therapy, used before surgery, is an important part of breast cancer treatment. Not only can it shrink tumors, but it can also provide valuable information on how the cancer responds to treatment, which can help physicians tailor further therapy. For aggressive types of breast cancer, such as HER2-positive and triple-negative breast cancers, targeted therapies and immunotherapy are often added to standard chemotherapy. Achieving a complete response to treatment (i.e., total absence of viable tumor from tissue removed during surgery) is usually a good sign, but it does not always mean better long-term outcomes for every patient. This review examines the evolution of neoadjuvant therapy in high-risk breast cancer and discusses recent clinical trials focused on optimizing treatment. It also highlights the need for new approaches to improve outcomes, especially for patients whose cancer does not fully respond to initial treatments.Abstract The use of neoadjuvant systemic therapy (NST) has become increasingly important in the treatment of breast cancer because of its various advantages. These include the ability to downstage tumors without compromising locoregional control and the potential to obtain valuable information about clinical and biological response to therapy with implications for individual prognoses. Surgical response assessment paves the way for response-adapted therapy, and pathological complete response (pCR; defined as ypT0/is ypN0) serves as an additional endpoint for drug development trials. Recommended NST regimens commonly consist of anthracyclines and taxane, with dose-dense anthracyclines and weekly paclitaxel often preferred, whenever feasible. For patients with human epidermal growth factor receptor-2 (HER2)-positive tumors, dual anti-HER2 therapy (trastuzumab and pertuzumab) is indicated together with NST in case of elevated risk of recurrence. For patients with triple-negative breast cancer (TNBC), adding carboplatin to NST correlates with improved pCR and survival rates, as does the addition of immune checkpoint inhibitors. For hormone receptor (HR)-positive/HER2-negative cancers, emerging data on NST including immune checkpoint inhibitors may elevate the significance of NST in high-risk luminal breast cancer. Here, we present a synthesis of the results from neoadjuvant clinical trials that aim at optimizing treatment options for patients with high-risk breast cancer.