ESR1 and cervical squamous intraepithelial neoplasia: (51) conducted a retrospective analysis of 2125 breast cancer patients from 13 studies and reported that the extent of CIN of ER-/HER2- breast cancer was significantly higher than that of ER+ breast cancer, and the extent of CIN of basal cell-like breast cancer was the highest (52), indicating that CIN is a manifestation of high-risk breast cancer subtypes.