ESR1 and breast cancer: In breast cancer, approximately forty driver genomic alterations in well-known oncogenes and tumor suppressor genes (TSGs) such as BRCA1/2, TP53, PIK3CA, ESR1, PTEN, PALB2, GATA3, KMT2C, NCOR1, AKT1, NF1, CDH1, and RB1, as well as in a number of novel genes including TBX3, RUNX1, CBFB, AFF2, PIK3R1, PTPN22, PTPRD, SF3B1, and CCND3, have been reported [56,57,58].