Endocrine therapy response and 21-gene expression assay for therapy guidance in HR+/HER2- early breast cancer

In HR-positive, HER2-negative early breast cancer (EBC), it is still questionable which patients need chemotherapy (CT) in addition to endocrine therapy (ET). The phase 3 WSG-ADAPT-HR+/HER2- trial in Germany investigated guidance of systemic therapy based on a gene expression assay and response to 3-week preoperative ET in patients with regional lymph node status 0-1. The study found that among patients with HR-positive, HER2-negative early breast cancer and three or less involved lymph nodes, guiding systemic treatment by both RS and ET response was feasible in clinical routine and spared chemotherapy in both pre- and postmenopausal patients.