Real-world Data on First-line Systemic Therapy for Hormone Receptor-positive HER2-negative Metastatic Breast Cancer: A Trend Shift in the Era of CDK 4/6 Inhibitors

• Published in: Clinical breast cancer Vol. 21; no. 6; pp. e688 - e692
• Main Authors: Werutsky, Gustavo, Reinert, Tomás, Rosa, Mahira Lopes, Barrios, Carlos Henrique
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-12-2021
• Subjects: Antineoplastic Agents, Hormonal - therapeutic use; Antineoplastic Combined Chemotherapy Protocols - therapeutic use; Breast Neoplasms - drug therapy; Breast Neoplasms - metabolism; Breast Neoplasms - pathology; Chemotherapy; Cyclin-dependent kinase 4-6; Databases, Factual; Epidemiology; Estrogen receptor; Female; Humans; Neoplasm Staging; Real word evidence; Receptor, ErbB-2 - metabolism; Receptors, Progesterone - metabolism; Risk Factors; Estrogen receptor; Chemotherapy; Cyclin-dependent kinase 4-6; Epidemiology; Real word evidence
• ISSN: 1526-8209; 1938-0666
• DOI: 10.1016/j.clbc.2021.04.003

Hormone receptor-positive (HR+) human epidermal growth factor receptor-2 negative (HER2–) tumors represent the most common subtype of metastatic breast cancer (MBC). International guidelines clearly state that endocrine therapy (ET) should be considered the preferred first-line therapy for these patients in the absence of very symptomatic visceral disease or evidence of endocrine resistance. Nonetheless compliance with guidelines significantly vary worldwide for many different reasons. Historically, a substantial proportion of patients with HR+ HER2– MBC have been treated with chemotherapy (CT) in first-line setting, jeopardizing patients’ quality of life without a significant benefit in outcome. In 17 observational studies, including more than 63,000 patients, ET was most frequently used in first-line treatment of HR+/HER2– MBC (range, 42%-87%), nonetheless a high proportion of patients received CT (13%-66%) as initial therapy. More recently, results of clinical trials with CDK 4/6 inhibitors improved response, progression-free and overall survival in this population and are currently the standard of care. There was a trend toward increased use of ET in recent years. This review article aims to evaluate real-world data on patterns of first-line treatment of HR+ HER2– MBC with a special focus on the use of CT in this setting and the potential implications and perceived preliminary changes after the introduction of CDK 4/6 inhibitors.