Endocrine Treatment and Targeted Therapy for HR-Positive, HER2-Negative Metastatic Breast Cancer

Publication Date: May 17, 2023
Last Updated: May 23, 2023

Summary of Recommendations

Recommendations from 2023 Rapid Recommendation Update

To aid in treatment selection, the Expert Panel recommends routine testing for emergence of ESR1 mutations at recurrence or progression on ET (with or without CDK4/6 inhibitor) in patients with ER-positive, HER2-negative MBC. Testing with a CLIA-certified assay should be performed on blood or tissue obtained at the time of progression, as ESR1 mutations develop in response to selection pressure during treatment and are typically undetectable in the primary tumor; blood-based ctDNA is preferred owing to greater sensitivity. If not performed earlier, testing for PIK3CA mutations should also be performed to guide further therapy. Patients whose tumor or ctDNA tests remain ESR1 wildtype may warrant retesting at subsequent progression(s) to determine if an ESR1 mutation has arisen. ( EB , H , B , S )
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Overview

Title

Endocrine Treatment and Targeted Therapy for HR-Positive, HER2-Negative Metastatic Breast Cancer

Authoring Organization