2. Patients have been diagnosed with metastatic triple-negative breast cancer (mTNBC). ER, PgR, and HER2 status were determined locally by immunohistochemistry (IHC) of patients' primary or metastatic tumor sections. ER-negative and PgR-negative status was defined as≤1% staining in the nuclei by IHC. HER2-negative status was defined by IHC staining 0 to 1+ or fluorescence in situ hybridization ratio \<2.0 if IHC 2+ or IHC not performed.
3. The metastatic disease was confirmed by clinical, imaging, histological, or cytological measures, including unresectable locally advanced breast cancer, de novo stage IV breast cancer, and recurrent metastatic breast cancer.
4. Patients who have received at least 1 prior regimen in the metastatic setting.
5. Plan to receive or has received sacituzumab govitecan monotherapy or chemotherapy of the physician's choice.
6. Available medical history.
7. All patients can provide an informed consent before enrolment and data collection.
You may not be if
1. If participating in any controlled clinical trial, the subject cannot take part in this study.
2. HER2 overexpression or gene amplification, ie, immunohistochemistry (IHC) 3+ or fluorescence in situ hybridisation (FISH)+, where appropriate.
