ERBB2 and non-small cell lung carcinoma: Unlike common epidermal growth factor receptor gene (EGFR) mutations that confer sensitivity to tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC), mutations in exon 20 of either EGFR or the human EGFR2 gene (HER2) are associated with insensitivity to EGFR-TKIs, with treatment options for patients with such mutations being limited.