Molecular Tumor Board: 59-year-old woman with ESR1 mutant hormone receptor-positive breast cancer

In this Molecular Tumor Board, our Medical Affairs team discussed a case of metastatic hormone receptor (HR)-positive breast cancer where limited tissue precluded tissue-based molecular profiling. A plasma-based ctDNA assay identified an ESR1 mutation associated with endocrine resistance, highlighting the value of liquid biopsy in guiding treatment decisions. This case reinforces the role of liquid biopsy in precision oncology and the importance of assessing ESR1 status in management of HR-positive breast cancer.