As in previous studies (8, 31, 32), the results of this study also suggest that biosimilar trastuzumab may provide treatment as safe and effective as RTZ, but at a remarkably presented opportunity for cost-saving and thereby to improved access for patients of HER2 positive breast cancer.This real-world study suggests that the biosimilar CT-P6 has similar effectiveness and cardiac safety to RTZ in HER2-positive EBC and MBC, when administered as part of dual HER2-targetd therapy with pertuzumab and chemotherapy in the neoadjuvant or palliative first-line setting. This evidence concerns the gene ERBB2 and breast cancer.