Hou Y, et al. - In this study, researchers intended to review the evaluation of human epidermal growth factor receptor 2 (HER2)status and its clinical application in breast cancer. Augmentation and overexpression of HER2 in breast cancer was related to an adverse prognosis. Adding trastuzumab and lapatinib was discovered to have substantially enhanced the clinical outcomes of individuals with HER2-positive breast cancer. The essential component of the successful application of anti-HER2 therapies in the real-world had been the choice of participants for treatment on the basis of the level of HER2 positivity of the tumor. Clinical evaluation of HER2 status of breast cancer is done by HER2 protein expression with immunohistochemistry (IHC) or HER2 gene amplification with in situ hybridizations. Moreover, digital image analysis (DIA) has emerged as an aim and reproducible IHC scoring method and the 2018 American Society of Clinical Oncology and the College of American Pathologists HER2 guideline has recognized DIA as a diagnostic modality.