ESR1 and breast cancer: Breast cancer risk factor associations vary by tumor subtypes.[13, 15–17] Given that risk prediction models were developed to estimate overall invasive breast cancer risk in populations screened with mammography, these models may demonstrate greater accuracy in predicting risk of estrogen receptor (ER) positive cancers and indolent tumors, which are frequent in this setting.[18–22] However, the performance of these models in predicting risk of fatal breast cancers, as would be needed to design trials to reduce breast cancer mortality, is largely unknown.