<h4>Background</h4>Epidermal growth factor receptor (EGFR) mutations have a low incidence in squamous cell lung cancer (SqCLC), and the clinical efficacy of EGFR tyrosine kinase inhibitors (TKIs) in <i>EGFR</i>-mutated SqCLC is far less than that in <i>EGFR</i>-mutated lung adenocarcinoma. This evidence concerns the gene EGFR and lung adenocarcinoma.