ESR1 and neoplasm: To investigate the potential clinical impact of A-to-I editing, we determined whether the mean editing frequency was associated with the tumor cell content (i.e., the proportion of malignant epithelial cells, adipose, stroma, normal epithelial cells and TILs) and/or well-established clinico-pathological parameters, including estrogen receptor, progesterone receptor, the proliferation marker Ki67, HER2 status, tumor size, nodal status, and histological grade.