PRIMARY OBJECTIVES:~I. To identify subtype-specific signatures for breast cancer using genomic positioning of plasma deoxyribonucleic acid (DNA) fragments.~II. To validate changes in circulating tumor-derived DNA (ctDNA) levels as a biomarker for treatment monitoring in patients with metastatic breast cancer.~OUTLINE:~Patients undergo collection of blood samples at baseline, 2 weeks after the start of treatment, and at the beginning of each new treatment cycle.
This study evaluates if blood tests can detect changes in disease status during treatment for stage IV breast cancer. Information from this study may help researchers learn more about metastatic breast cancer and how to optimize treatment.