Evidence from the literature on patients with EGFR-mutated NSCLC indicates that disease progression after TKIs occurs most often at sites of disease known to exist at baseline, supporting the idea of disease progression due to the development of TKI-resistant clones at the primary tumor site with subsequent systemic reseeding and widespread distant progression [14, 22–24]. This evidence concerns the gene EGFR and non-small cell lung carcinoma.