Use of Liquid Biopsy in the Care of Patients with Non-Small Cell Lung Cancer.

OPINION STATEMENT: Recent technological advances have enabled the development of liquid biopsy-based approaches, which have revolutionized the diagnostic world. The analysis of circulating tumor DNA (ctDNA) has several clinical applications. First, ctDNA genotyping is becoming widely used for non-invasive biomarker testing. Of note, in lung cancer patients in whom biopsies are difficult to obtain, ctDNA has led to significant improvement in the diagnosis and identification of therapeutic targets. In addition, ctDNA quantification over the course of the disease can be useful for tumor response to treatment monitoring and for early detection of resistance mutations. ctDNA levels per se are also of prognostic significance and could be used to tailor treatments. Finally, improvements in assay sensitivity are facilitating the development of liquid biopsy-based tests for the detection of ctDNA at very low allele frequencies (AFs), which can be used for the measurement of minimal residual disease and ultimately for the development of strategies (by complementing imaging techniques) aimed to improve the efficiency of lung cancer screening programs.