In conclusion, our results indicate that in patients with stage II-III HER2-positive breast tumors that are classified as HER2-type or HER2-single-type upon molecular characterization, the addition of pertuzumab to neoadjuvant chemotherapy and trastuzumab may improve pathological complete response and may decrease the risk of death due to breast cancer. The gene discussed is ERBB2; the disease is breast neoplasm.