Liquid biopsy and genomic assessment for lung cancer: The role in clinical practice?

The medical care of patients with advanced stage or metastatic lung cancer needs to evaluate the priorities for treatment of patients with targeted therapy or immunotherapy. In daily practice, evaluation is based on the presence or absence of biomarkers of interest that are detected in general with tissue samples and/or cells. Since it is easy to repeat and is noninvasive, the practice of liquid biopsies (LB) has been adopted by many hospitals. It allows evaluation over time of genomic biomarkers of therapeutic efficacy and resistance. Thus, the investigation of mutations in EGFR with a blood sample, while respecting certain conditions, is internationally recommended for the daily care of these patients. Recommendations for routine detection with LB are forthcoming for several genomic alterations, in particular for rearrangements in ALK and ROS1, or even for mutations in BRAF, for administration of targeted therapies. With the increasing use of targeted therapies and the emergence of resistance during treatment, the investigation of a single gene has progressed toward evaluation of a more or less extensive panel of genes. Before using LB in daily routine practice, it is essential to master the preanalytical, analytical, and postanalytical steps. Due to the technological and scientific progress made in the use of LB in thoracic oncology, many options are being proposed. However, the transfer of certain discoveries for the benefit of patients requires rigorous evaluation, demonstrating the reliability of the tests and their clinical validity. This chapter reviews the different elements concerning the present use and potential of evaluation of genomic alterations using LB obtained from patients with lung cancer.