The liquid biopsy: Its present and future

Cell free DNA, circulating tumor cell, and exosomes are collectively called liquid biopsy. The detection of molecular abnormalities in a liquid biopsy is a low-invasive technique that allows us to perform analyses and monitoring multiple times. Digital polymerase chain reaction and next-generation sequencing have improved the sensitivity and multiplicity of liquid biopsy analyses. Efforts to improve the detection of low-frequency mutation alleles further are now underway. Biological understanding of the cell free DNA with regard to aspects such as gene transfer and immune reactions have led to the development of cancer treatment regimens using liquid biopsies. In the clinical setting of lung cancer patients, serum EGFR mutation kits are available to identify patients indicated for third-generation EGFR-tyrosine kinase inhibitors. Liquid biopsies may eliminate the sampling bias caused by tumor heterogeneity and bring a paradigm shift to the adaptive treatment of lung cancer.