The Impact of Progesterone Receptor Status on Survival Outcomes in Metastatic Breast Cancer Patients Treated with First-Line CDK4/6 Inhibitors

Abstract

Over the past eight years, the addition of the cyclin-dependent kinase (CDK) 4/6 inhibitors in the management of patients with metastatic hormone receptor-positive breast cancer has dramatically improved clinical outcomes. Nevertheless, early progression may occur in a notable percentage of patients, and biomarkers that can predict treatment failure have not yet been precisely defined. Progesterone receptor (PgR) status is recognized as a significant biomarker for predicting prognosis in hormone-positive breast cancer; however, its impact on the efficacy of CDK 4/6 inhibitors remains a matter of debate. The aim of this study was to investigate the impact of PgR status on the prognosis of patients receiving first-line CDK4/6 inhibitors in combination with endocrine therapy. The expression level of PgR might be used as a cost-effective and accurate indicator for assessing the efficacy of CDK4/6 inhibitors.