HR-Positive Breast Cancer: ctDNA Trends, Monitoring Strategies, and the Need for Standardization

This segment explores the emerging use of circulating tumor DNA trends, including variant allele frequency, as a potential tool to guide monitoring in hormone receptor–positive, HER2-negative metastatic breast cancer. Dr. Adam Brufsky raises the question of whether ctDNA dynamics could inform clinical decisions such as timing of imaging or assessment of treatment response in the absence of definitive trial data.

Dr. Hope S. Rugo discusses the potential role of ctDNA as a surrogate marker, noting that rising levels may correlate with disease progression, while also emphasizing the limitations of current evidence and variability across patient populations.

Dr. Mabel Mardones highlights how ctDNA monitoring is already being used selectively in practice to reduce imaging burden in stable patients. However, Ms. Lori Brisbin underscores the critical need for assay standardization across platforms before widespread adoption. Overall, this segment highlights both the promise and complexity of ctDNA-guided monitoring.