Treatment Sequencing of ER+/HER2- Metastatic Breast Cancer and the Associated Healthcare Resource Utilization and Overall Cost of Care

Treatment sequencing in ER+/HER2- metastatic breast cancer has become increasingly complex as new endocrine therapies, targeted agents, and antibody–drug conjugates enter the landscape. Each step in the sequence influences not only clinical outcomes but also healthcare resource utilization and overall cost of care. Early use of CDK4/6 inhibitors has improved survival but adds significant drug and monitoring expenses. Subsequent lines—such as PI3K, mTOR, and SERD-based therapies—require genomic testing, frequent toxicity management, and specialized support, further increasing resource demands. Optimizing sequencing strategies that balance efficacy, tolerability, and economic impact is essential. Improved real-world evidence, biomarker-driven decisions, and coordinated care models can help reduce unnecessary utilization while maintaining high-quality cancer care.