The most frequently altered genes were TP53 (47%), PIK3CA (30%), GATA3 (18%), ESR1 (17%), KMT2C (10%), CDH1 (9%), PTEN (7%), and NF1 (7%); in the HR+/HER2- breast cancers, nine genes were the most frequently mutated in the metastatic setting, including TP53 (29%), ESR1 (22%), GATA3 (18%), KMT2C (12%), NCOR1 (8%), AKT1 (7%), NF1 (7%), RIC8A (4%), and RB1 (4%), with the TP53 and ESR1 genes being mutually exclusive [168]. This evidence concerns the gene ERBB2 and breast cancer.