Between March 2017 and May 2019, a total of 41 unique patients with EGFR-mutated NSCLC, treated with a 1st generation EGFR-TKI in first line or 3rd generation EGFR-TKI in second line for a EGFR p.T790M resistance mutation, were included. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.