ERBB2 and breast cancer: Although HER2-positive breast cancer is a biologically aggressive tumor, the revolution in HER2-targeted therapies has significantly improved the prognosis of patients with HER2-positive breast cancer [1,2].In addition, the application of neoadjuvant systemic therapy (NAST) in the early stages of HER2-positive breast cancer has increased because NAST has the benefit of reducing the surgical extent and tailoring adjuvant treatment according to its response [3,4].