Systemic therapy for early‐stage HER2‐positive breast cancers: Time for a less‐is‐more approach?

Trastuzumab-based chemotherapy has dramatically improved outcomes for patients with all stages of human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Additional HER2-directed agents that have recently been approved are also expected to improve outcomes. Patients with small, lymph node-negative, HER2-positive breast cancers who are treated with trastuzumab-based chemotherapy demonstrate especially favorable responses, with 5-year recurrence rates of <5%. In this review, recent data regarding response rates among patients with early-stage HER2-positive breast cancer treated with trastuzumab-based chemotherapy are discussed. This review supports future studies of the possible omission of chemotherapy in a subset of patients with HER2-positive cancers, specifically those that coexpress hormone receptors.