Observational Clinical Study on Role of MRD in Predicting Local Therapy in Oligometastatic Breast Cancer

Inclusion Criteria: 1. Histologically or cytologically confirmed breast cancer. 2. Previously confirmed metastatic breast cancer by imaging. 3. Eastern Cooperative Oncology Group (ECOG) physical status score of 0-2. (4) Age ≥ 18 years at the time of signing the informed consent form. (5) Subjects willing and able to comply with the study protocol throughout the study period. (6) Female subjects of childbearing potential must agree to use a highly effective method of contraception during the study. (7) Voluntarily agree to and sign a written informed consent form and be willing and able to comply with all aspects of the trial protocol, which can be withdrawn by the patient at any time without prejudice. Exclusion Criteria: 1. Patients with active/refractory infections that require ongoing anti-infective therapy. 2. Severe cardiovascular compromise (history of congestive heart failure greater than New York Heart Association (NYHA) class II), unstable angina or myocardial infarction within the past 6 months, or severe arrhythmia. 3. Subjects with allogeneic organ transplants requiring immunosuppressive therapy. (4) Subjects known to be human immunodeficiency virus (HIV) positive. 5\) Subjects with a prior malignancy other than breast cancer, cervical cancer in situ, and non-melanoma skin cancer, unless the prior malignancy has been previously diagnosed and definitively treated for at least 5 years without evidence of subsequent recurrence. 6\) Any medical condition that, in the opinion of the Investigator, makes the subject unsuitable for entry into the study.