We noticed two recent studies42,43 demonstrated that TP53, ESR1, PTEN, KMT2C, AKT1, and NF1 were more frequently mutated in the metastatic HR+/HER2− breast cancers compared with the early ones, in accordance with the previous study15, indicating their driving impact in breast cancer metastasis and relapse. The gene discussed is ERBB2; the disease is breast cancer.