Although the vast majority of these patients will recur or progress on treatment, the availability of 2nd and 3rd generation targeted therapies for emerging resistance mutations in EGFR and ALK fusion driven lung cancer has prolonged intervals of disease-free survival [2, 3], leading to recommendations to repeat biopsies for genotyping lung cancer patients progressing after first line targeted therapies. The gene discussed is EGFR; the disease is lung carcinoma.