ESR1 and neoplasm: There were also no significant differences in age, BMI, menstrual status, lesion position, LN stage, histological type, ER status, PR status, Ki67, BI-RADS, tumor shape, and color Doppler flow between the training and validation cohorts; however, differences in some clinicopathologic characteristics were observed in patients of these two cohorts owing to the spatial span of the different institutions, according to our study.