In 2016, a 38-year-old female patient underwent a right mastectomy with ipsilateral sentinel nodal dissection for a pT2N1mi(sn) non-specific infiltrating ductal carcinoma (SBR grade 3, Estrogen Receptor (ER) negative, Progesterone Receptor (PR) negative, HER2 3+, positive vascular emboli). This evidence concerns the gene ESR1 and invasive ductal breast carcinoma.