Clinical implementation and current advancement of blood liquid biopsy in cancer

Liquid biopsies have been receiving tremendous attentions as easy, rapid, and non-invasive tools for cancer diagnosis. Liquid biopsy can be performed repeatedly for disease monitoring and is expected to overcome the limitations of tissue biopsies. With the advancement of next generation sequencing technologies, it is now possible to detect minute amount of tumor-derived circulation tumor DNA (ctDNA) from blood samples. Importantly, ctDNA detection could be complementary to tissue biopsies or tumor biomarkers particularly in cases of which tumor biopsy is clinically difficult to obtain. Here, we introduce the up-to-date technologies used in cfDNA-based liquid biopsy and review the clinical utilities of ctDNA in cancer screening, detection of minimal residual diseases, selection of molecular-targeted drugs, as well as monitoring of treatment responsiveness. We also discuss the challenges and future perspectives of liquid biopsy implementation in clinical setting.