The anticipated objectives of this study are: 1) to understand the pathogenesis and molecular typing of breast cancer patients in China (mainly HER2 overexpression, triple negative and hormone receptor-positive patients) by detecting DNA and RNA in tumor tissue (fresh tissue or paraffin section), and to compare the similarities and differences between the western population and Chinese population; 2) plasma samples of patients with HER2 overexpression , hormone receptor-positive and triple negative (ER, PR, HER2 expression negative) were sequenced for ctDNA and ctRNA, to find out whether there are genes or gene sets related to therapeutic effect; 3) to study the specific changes of liquid molecular detection results according to the previous research results, and establish mathematical models to predict and monitor the effects of targeted therapy and endocrine therapy; 4) to compare liquid biopsy and imaging and clinical features in monitoring clinical therapeutic effect, and to elaborate the advantages and disadvantages of liquid biopsy and conventional imaging; 5) to provide molecular detection basis for follow-up clinical research and screening for targets of new drugs.

Inclusion Criteria:

• patients with first treated or recurrent metastatic breast cancer, according to RECIST version 1.1 standard, confirmed by CT or MRI, have at least one measurable lesion.
• HER2 positive or triple negative patients; (IHC++, fish amplification)
• Patients with anti-HER2 treatment as first-line or not, and patients with HER2 positive can be treated with adjuvant therapy containing trastuzumab.

Exclusion Criteria:

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Patients of breast cancer in China mainly with HER2 overexpression, triple negative and hormone receptor-positive.