Liquid biopsy represents a procedure for minimally invasive analysis of non-solid tissue, blood and other body fluids. It comprises a set of analytes that includes circulating tumor cells (CTCs) and circulating free DNA (cfDNA), RNA, long noncoding RNA (lncRNA) and micro RNA (miRNA), as well as extracellular vesicles. These novel analytes represent an alternative tool to complement diagnosis and monitor and predict response to treatment of the tumoral process and may be used for other disease processes such viral and parasitic infection. This review focuses on the biologic and molecular characteristics of cfDNA in general and the molecular changes (mutational and epigenetic) proven useful in oncologic practice for diagnosis, monitoring and treatment of breast cancer specifically.
Keywords: Biomarker; Breast cancer; CTC; ESR1; Exosomes; Liquid biopsy; Methylation; PIK3CA; cfDNA; ctDNA.
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