Preferences in Cyclin-Dependent Kinase 4/6 Inhibitors for Advanced Breast Cancer Among Medical Oncologists in Latin America

PURPOSE Cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) have redefined the standard of care for hormone receptor–positive, human epidermal growth factor receptor 2–negative advanced breast cancer (BC). However, patterns of use and access across Latin America remain poorly characterized. METHODS We conducted a cross-sectional survey of Latin American medical oncologists with experience in treating advanced BC using CDK4/6i. The survey assessed drug availability and clinical decision making across various scenarios. Descriptive statistics were used to summarize responses. RESULTS A total of 116 oncologists from 15 countries participated. Ribociclib was the preferred agent (56.8%), driven largely by its overall survival benefit across pivotal trials. Abemaciclib was favored in endocrine resistance, central nervous system metastases, and patients with cardiac or hepatic comorbidities. Palbociclib was preferred in geriatric and male patients. Despite high reported national availability of CDK4/6i, access at the institutional level was uneven. Among oncologists working primarily in private practice, 54.3% reported that their prescribing patterns would differ if treating publicly insured patients, compared with only 22.6% of public sector oncologists who reported the opposite. CONCLUSION Although CDK4/6i are accepted as essential therapies for advanced BC, substantial institutional access barriers persist in Latin America. Clinical preferences reflect both emerging evidence and local constraints. Broader integration of CDK4/6i into public formularies and continuous generation of real-world data are critical for improving equity and outcomes in the region.