ShortStop-HER2: Shortened Duration of Adjuvant Therapy in Patients with Early-Stage HER2+ Breast Cancer Who Achieve pCR After Neoadjuvant Chemotherapy with HER2 Blockade

This study is being done to answer the following question: Among patients with early-stage HER2+ breast cancer who have a pCR after preoperative chemotherapy with trastuzumab, will 6 months of HER2-targeted medications be as effective as 12 months of HER2-targeted medications at preventing cancer from coming back? We are doing this study because we want to find out if 6 months of HER2-targeted medications is as good as the usual approach for your breast cancer. The usual approach is defined as care most people get for breast cancer.