ESR1 and breast cancer: In the same way, the prognostic role of the 21-gene OncotypeDX © recurrence score was established in high-expressing Estrogen Receptor (ESR1) breast cancers based on results from the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-28 and B-14 clinical trials [47] and independently from ESR1 expression in the TransATAC cohort [48].