The highly significant correlation of PA1-nuc/ -cyto with ERα, a well-established/widely accepted endocrine therapy responsiveness index, might suggest that PA1 is of potential value to be a candidate for endocrine therapy responsive indicator and therefore increase the accuracy of prediction in combination with ERα, which warrants further confirmation in a well-defined cohort of endocrine treated breast cancer patients. Here, ESR1 is linked to breast carcinoma.