Early Stage HER2+ Breast Cancer

The main purpose of this study is to evaluate the impact of a decentralized treatment model on treatment adherence in participants with early-stage human epidermal growth factor receptor 2- positive (HER2+) breast cancer (BC). This study has 2 groups: Group 1: Consistent Travel Burden (Cohorts A, C, and D), will include participants whose adjuvant therapy location does not increase their travel requirements, and Group 2: Increased Travel Burden (Cohort B), will include participants who must travel from a secondary center to a tertiary center to receive their adjuvant therapy.

This phase III trial compares 6 months of human epidermal growth factor receptor 2 (HER2)-targeted therapy to 12 months of HER2-targeted therapy for the treatment of HER2-positive (+) breast cancer in patients that had a pathologic complete response (pCR) after preoperative (neoadjuvant) chemotherapy with trastuzumab. Trastuzumab and pertuzumab are monoclonal antibodies and forms of targeted therapy that attach to a receptor protein called HER2. HER2 is found on some cancer cells. When trastuzumab or pertuzumab attach to HER2, the signals that tell the cells to grow are blocked and the tumor cell may be marked for destruction by the body's immune system. Giving 6 months of HER2-targeted therapy may work better than giving 12 months for the treatment of HER2+ breast cancer in patients that had a pCR after neoadjuvant chemotherapy with trastuzumab.