This study is a multicenter, retrospective, real-world cohort study. It retrospectively collected data from HER2-positive breast cancer patients who received neoadjuvant therapy with trastuzumab-containing chemotherapy regimens and had Non-pCR after surgery between July 2019 and July 2025. Patients were divided into two groups based on their adjuvant treatment regimens: the trastuzumab combined with pertuzumab group (HP) and the ado-trastuzumab emtansine group (T-DM1). The planned sample size is 2000 cases.
Histopathologically confirmed HER2-positive breast cancer (i.e., immunohistochemistry (IHC) staining result of 3+, or HER-2 2+ with fluorescence in situ hybridization showing HER-2 gene amplification);
Received neoadjuvant therapy with chemotherapy combined with trastuzumab before surgery: including at least 6 cycles of chemotherapy, with at least 4 cycles of taxane-based chemotherapy; and at least 4 cycles of trastuzumab treatment (including trastuzumab biosimilars and subcutaneous formulations);
Completion of radical surgery, postoperative pathology confirms the presence of invasive carcinoma in the breast and/or axillary lymph nodes after neoadjuvant therapy.
Hormone receptor status is known.
Combine other systemic malignant tumors, excluding cured basal cell carcinoma of the skin and cervical carcinoma in situ;
Stage IV metastatic breast cancer;
Incomplete clinical pathology and follow-up data; Study endpoints