Abstract
BACKGROUND: Circulating cell-free DNA (cfDNA) isolated from plasma or serum by noninvasive procedures can serve as a "liquid biopsy" and has potential as a biomarker for the tumor burden and survival prediction of breast cancer (BC). However, its prognostic value in patients with BC is currently under debate. The aim of this meta-analysis was to investigate the relationship between cfDNA and survival outcome. METHODS: We systematically searched PubMed, Embase, and Science Citation Index electronic databases for studies about the prognostic utility of cfDNA in patients with BC. The clinical characteristics, relapse/disease-free survival (RFS/DFS), and overall survival (OS) data were extracted from the eligible studies. The hazard ratios (HR) and 95% confidence intervals (CI) were calculated and pooled with a fixed-effects model using the Stata12.0 software. Subgroup and sensitivity analyses were also performed. RESULTS: This meta-analysis included a total of 10 eligible studies and 1127 patients with BC. The pooled HR with 95% CI showed strong associations between cfDNA and OS (HR = 2.41, 95% CI, 1.83-3.16) along with DFS/RFS (HR = 2.73, 95% CI, 2.04-3.67) in patients with BC. Although publication bias was found in the studies regarding RFS/DFS, further trim and fill analysis revealed that the adjusted HR would be 2.53 (95% CI, 1.83-3.51), which is close to the original HR. Subgroup analyses confirmed the role of cfDNA as a strong prognostic marker in patients with BC, regardless of cfDNA analysis, sampling time, sample source, detection method, tumor stage, sample size, or area. CONCLUSIONS: Our meta-analysis indicates that cfDNA is a strong predictive and prognostic marker in patients with BC.