In this study, prognosis for the EarlyR-Low patients in the overall ER+ postmenopausal breast cancer cohort was excellent, with the estimated 8-year DRFI being 91% (95% CI = 89% to 92%), and in ER+/LN− patients not treated with chemotherapy the estimated 8-year DRFI was 95.4% (95% CI = 94% to 96.8%) and estimated 8-year BCFI was 92.5% (95% CI = 90.8% to 94.3%). This evidence concerns the gene ESR1 and breast cancer.