Abstract

Metastatic hormone receptor positive (HR+)/human epidermal growth factor receptor-2 negative (HER2−) breast cancer continues to be a significant cause of cancer-related death. First-line treatment with a cyclin-dependent kinase 4 and 6 inhibitor (CDK4/6i) has become the standard to improve quality of care and delay time to chemotherapy. However, following CDK4/6i progression, prognosis is poor and optimal second line treatment is not clearly defined. This research aims to identify and assess current treatment patterns for patients with HR+/HER2-metastatic breast cancer (MBC) after first-line therapy CDK4/6i progression.