Plasma cell-free DNA (cfDNA) as a predictive and prognostic marker in patients with metastatic breast cancer.

Background: Breast cancer (BC) is the most common cancer in women, and despite the introduction of new screening programmes, therapies and monitoring technologies, there is still a need to develop more useful tests for monitoring treatment response and to inform clinical decision making. The purpose of this study was to compare circulating cell-free DNA (cfDNA) and circulating tumour cells (CTCs) with conventional breast cancer blood biomarkers (CA15-3 and alkaline phosphatase (AP)) as predictors of response to treatment and prognosis in patients with metastatic breast cancer (MBC).

Methods: One hundred ninety-four female patients with radiologically confirmed MBC were recruited to the study.