This is an prospective, multicenter, single-arm clinical study.
Age ≥18 years old;
Signed the informed consent and volunteered to join the study with good compliance;
HER2 negative was defined as 0/1+ on standard IHC test; HER2/CEP17 ratio was less than 2.0 or HER2 gene copy number was less than 4.
ER positive and/or PR positive were defined as the proportion of positively stained tumor cells in all tumor cells ≥1%;
Stage IV (metastatic) breast cancer;
Received treatment for the disease, including chemotherapy, endocrine therapy, radiotherapy, immunotherapy, etc.;
Patients who are participating in other intervention studies;
Women with confirmed pregnancy or lactation;