<h4>Background</h4>De novo (pretreatment) <i>EGFR T790M</i> mutation is a rare molecular finding in non-small cell lung cancer (NSCLC) and has historically been associated with primary resistance to first- and second-generation EGFR tyrosine kinase inhibitors (TKIs). This evidence concerns the gene EGFR and non-small cell lung carcinoma.