Currently, tumor alterations in PIK3CA, AKT1, PTEN, ESR1, HER2, NTRK1/2/3, RET, and germline or somatic alterations in BRCA1/2 genes, germline PALB2 (gPALB2) alterations, as well as microsatellite instability (MSI) and high tumor mutation burden (TMB) represent actionable biomarkers in breast cancer.3 This evidence concerns the gene ERBB2 and breast carcinoma.