According to the preliminary results of the current study, a potential stepwise algorithm for p.T790 M mutation detection for patients with advanced NSCLC and acquired resistance to first or second‐generation EGFR‐TKIs, starting with sputum supernatant cfDNA testing (Figure 2): sputum sample and plasma samples are simultaneously collected, sputum sample pathological evaluated was proposed. This evidence concerns the gene EGFR and non-small cell lung carcinoma.