EGFR and non-small cell lung carcinoma: Plasma circulating tumour DNA (ctDNA) is a non‐invasive method that has been used to identify EGFR mutations and other genetic drivers in NSCLC and in response to treatment of NSCLC patients with EGFR‐TKIs (Yung et al, 2009; Couraud et al, 2014; Douillard et al, 2014; Newman et al, 2014, 2016; Weber et al, 2014; Paweletz et al, 2015; Wan et al, 2017).