Update on EGFR Mutational Testing and the Potential of Noninvasive Liquid Biopsy in Non-Small-cell Lung Cancer

Mutations in the epidermal growth factor receptor (EGFR) are important drivers of non-small-cell lung cancer (NSCLC) and have led to the emergence of EGFR-targeted therapies as critical treatment options for NSCLC. Although these agents have shown clinical activity in NSCLC patients, acquired resistance to EGFR-targeted agents is inevitable. Therefore, the ability to conveniently biopsy patient tumors is of increasing importance as new mechanisms of resistance and agents to target these resistance mutations are identified. Rapid and accurate EGFR mutational testing of patient biopsy specimens, including liquid biopsy specimens, allows for the identification of potentially actionable mutations that could guide treatment. In the present review, we discuss the various methods and best practices for tumor sampling and EGFR mutational testing in NSCLC.