Effect of Epidermal Growth Factor Receptor Tyrosine Kinase Domain Mutations on the Outcome of Patients with Non–Small Cell Lung Cancer Treated with Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors

Somatic mutations in the epidermal growth factor receptor (EGFR) have been identified in patients with advanced non-small cell lung cancer who achieve dramatic clinical and radiographic response to the EGFR tyrosine kinase inhibitors (TKI) gefitinib and erlotinib. These mutations in EGFR are found more frequently in patients with adenocarcinomas, nonsmokers, patients of Asian ethnicity, and in females: the same populations that are the most likely to have a clinical response when treated with EGFR TKIs. Retrospective studies comparing the outcomes of patients with and without EGFR mutations treated with EGFR TKIs show a significant clinical benefit of EGFR TKIs in patients with EGFR mutations. These findings suggest that for patients with advanced non-small cell lung cancer bearing EGFR mutations, treatment with an EGFR TKI should be incorporated as at least part of their initial therapy. These approaches are being studied in ongoing clinical trials and will spur the development of additional technology for EGFR mutation detection.