Current guidelines lack definitive evidences about the relative benefits of locoregional surgery for the primary tumor in de novo stage IV breast cancer. The aim of this study (SYSBTC-001) was to investigate the role of locoregional surgery for primary tumor in de novo stage IV breast cancer.

Inclusion Criteria:

• Operable stage IV breast cancer patients,whose primary lesion is invasive breast cancer confirmed by pathology, and metastases can be confirmed by pathology or imageology examination.
• ECOG-PS 0-2.
• Bone marrow, liver and kidney should be fully functional.
• Patients received the locoregional surgery of the primary tumor in de novo in our center, or didn't received the locoregional surgery of the primary tumor in de novo.
• For the patient who accepted systematic treatment before operation, the systematic treatment must be administered within a year since diagnosed.

Exclusion Criteria:

• Accompanied with other primary malignant tumors.
• Patients who can't plan for follow-up effectively and regularly.
• Multiple liver metastasis and ALT/AST four times higher than normal at patients' first diagnosis.

Operable stage IV breast cancer patients, whose primary lesion is invasive breast cancer confirmed by pathology, and metastases can be confirmed by pathology or imaginology examination