Real-world estrogen receptor alpha 1 (ESR1) testing patterns and results for ER+/HER2- metastatic breast cancer in the United States, 2018–2024
To understand historical and recent ESR1 testing rates, and when ESR1 mutations emerge during first-line (1 L) treatment. This retrospective, observational cohort study used the Flatiron Health Research Database (FHRD) and the Flatiron Health-Foundation Medicine metastatic breast cancer (mBC) Clinico-Genomic Database (...