ESR1 Mutations in Primary Breast Cancer
December 7, 2025 • ESR1 Mutated ER HER2 Advanced Breast Cancer Content Hub
Suzanne A. W. Fuqua, PhD, Baylor College of Medicine, explains that while the role of ESR1 mutations in primary breast cancer remains controversial, earlier studies have reported specific mutations (like K303R) in some premalignant and primary tumors, suggesting such mutations may exist before metastatic progression. She emphasizes that more research is needed to confirm how frequently these mutations occur and whether they meaningfully affect response to endocrine therapy in early-stage disease.
