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.
