During the initial EGFR‐TKI exposure, 7 of 35 patients (20.0%) discontinued therapy due to AEs (CTCAE ≥ grade 3), most commonly dermatologic toxicity (rash with gefitinib [n = 1], rash with erlotinib [n = 1], paronychia with afatinib [n = 1]), hepatotoxicity (gefitinib [n = 1], erlotinib [n = 1]), and pneumonitis (afatinib [n = 1; grade 4], osimertinib [n = 1]). This evidence concerns the gene EGFR and pneumonitis.