Patients and data collection
leptomeningeal disease, disability
ONCOLOGY, BRAIN METASTASIS, METASTATIC DISEASE
From November 1, 2018, to March 31, 2021, female patients aged ≥ 18 years old with histologically confirmed HER2-positive MBC at National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital (Shenzhen, Guangdong, China) were enrolled in this study. HER2 status was determined by central review based on immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH) examination using primary or metastatic lesion samples. Patients had been previously treated with trastuzumab, pertuzumab and/or lapatinib in the (neo)adjuvant/metastatic setting. Additional requirements included an Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1 (on a 5-point scale by which greater scores reflect higher degree of disability); measurable lesions; and adequate organ function. Patients were excluded if they had previously received treatment with pyrotinib for metastatic disease; had symptomatic brain metastasis which necessitates immediate local intervention; or had leptomeningeal disease. All procedures performed involving human participants were in accordance with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. This study was also approved by the institutional review board and ethics committee. All patients provided written informed consent for use of the medical information for research purpose.