Analysis of PIK3CA mutations in the primary and recurrent tumors of hormone receptor positive/human epidermal growth factor receptor 2 negative breast cancer

Our aim was to compare the PIK3CA mutation status in matched primary and recurrent tumors of hormone receptor positive/human epidermal growth factor receptor 2 negative (HR+/HER2-) breast cancer (BC) to gain insight into the optimization of patient selection and detection time for PIK3CA-targeted therapy.