McArthur, Heather

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype characterized by lack of estrogen receptor expression, progesterone receptor expression, and human epidermal growth factor 2 overexpression/amplification. Given its generally aggressive biology, current guidelines recommend systemic therapy for most patients, with anthracycline- and taxane-based regimens being historically preferred. However, the clinical outcomes of patients with stage I TNBC and the benefit (or lack thereof) of (neo)adjuvant chemotherapy have not been prospectively evaluated as this population has largely been excluded from prospective randomized clinical trials. As such, management decisions for stage I TNBC are typically extrapolated from trials enrolling patients with stage II or III TNBC or based on retrospective analyses. Currently, the primary factor influencing systemic therapy decisions is the anatomic stage, without other biomarkers clinically used to guide systemic therapy. This review summarizes the existing evidence supporting current and emerging systemic therapy strategies for stage I TNBC, with a special focus on treatment de-escalation and promising biomarkers that can advance personalized treatment selection.