ERBB2 and breast cancer: Efforts to evaluate less toxic adjuvant regimens for small HER2-positive breast cancer have been conducted9, and based on the excellent efficacy outcomes in the adjuvant paclitaxel and trastuzumab (APT) study10,11, adjuvant paclitaxel with trastuzumab (TH) is currently considered a standard option for patients with stage I HER2-positive breast cancer12,13.