In lung cancer, a genetic test for epidermal growth factor receptor (EGFR) mutations is a critical diagnostic tool, because the clinical efficacy of first- and second-generation EGFR tyrosine kinase inhibitors (EGFR-TKI) has been well established for drug-sensitive and -resistant EGFR-mutated non-small-cell lung carcinomas [1,2]. The gene discussed is EGFR; the disease is lung cancer.