EGFR and non-small cell lung carcinoma: Unlike most other primary epidermal growth factor receptor (<i>EGFR</i>) mutations in non-small cell lung cancer (NSCLC), exon 20 insertions, comprising approximately 4% to 10% of all <i>EGFR</i> mutations, are generally considered to be resistant to EGFR tyrosine kinase inhibitors (TKIs).