EGFR and lung cancer: Notably, the use of liquid biopsy is supported in clinical guidelines for advanced lung cancer, and the assays Guardant360® CDx (Guardant, Palo Alto, CA) and FoundationOne®Liquid CDx (Foundation Medicine, Inc., Cambridge, MA, USA) have received FDA approval as companion diagnostics across a range of biomarkers, including for EGFR-mutated NSCLC [16–20].